<PAGE>

                                                                   EXHIBIT 2(b)5

================================================================================

                     MAXCOM TELECOMUNICACIONES, S.A. DE C.V.

                                     Issuer

                 CORPORATIVO EN TELECOMUNICACIONES, S.A. DE C.V.

                 MAXCOM SERVICIOS ADMINISTRATIVOS, S.A. DE C.V.

                                MAXCOM USA, INC.

                                   Guarantors

                          SENIOR STEP-UP NOTES DUE 2009

                               -------------------

                                    INDENTURE

                           Dated as of October 8, 2004

                               -------------------

                              THE BANK OF NEW YORK

                                     Trustee

================================================================================

<PAGE>

                             CROSS-REFERENCE TABLE*

<TABLE>
<CAPTION>
Trust                              Indenture
Act Section                                                                       Indenture Section
<S>                                                                               <C>
310(a)(1).................................................................               7.10
         (a)(2)...........................................................               7.10
         (a)(3)...........................................................               7.12
         (a)(4)...........................................................               N.A.
         (a)(5)...........................................................               7.10
         (b)..............................................................               7.10
         (c)..............................................................               N.A.
311(a)   .................................................................               7.11
         (b)..............................................................               7.11
         (c)..............................................................               N.A.
312(a)   .................................................................               2.05
         (b)..............................................................              12.03
         (c)..............................................................              12.03
313(a)   .................................................................               7.06
         (b)(1)...........................................................               N.A.
         (b)(2)...........................................................               7.07
         (c)..............................................................            7.06;12.02
         (d)..............................................................               7.06
314(a)   .................................................................            4.03;12.02
         (b)..............................................................               N.A.
         (c)(1)...........................................................              12.04
         (c)(2)...........................................................              12.04
         (c)(3)...........................................................               N.A.
         (d)..............................................................               N.A.
         (e)..............................................................              12.05
         (f)..............................................................               N.A.
315(a)   .................................................................               7.01
         (b)..............................................................            7.05,12.02
         (c)..............................................................               7.01
         (d)..............................................................               7.01
         (e)..............................................................               6.11
316(a)   (last sentence)..................................................               2.09
         (a)(1)(A)........................................................               6.05
         (a)(1)(B)........................................................               6.04
         (a)(2)...........................................................               N.A.
         (b)..............................................................               6.07
         (c)..............................................................               2.12
317(a)(1).................................................................               6.08
         (a)(2)...........................................................               6.09
         (b)..............................................................               2.04
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
Trust                                             Indenture
Act Section                                                                       Indenture Section
<S>                                                                               <C>
318(a)   .................................................................              12.01
         (b)..............................................................               N.A.
         (c)..............................................................              12.01
</TABLE>

N.A. means not applicable.

* This Cross-Reference Table is not part of the Indenture.

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                                   Page
<S>                                                                                                                <C>
ARTICLE 1 DEFINITIONS AND INCORPORATION BY REFERENCE.........................................................        1
   SECTION 1.01      DEFINITIONS.............................................................................        1
   SECTION 1.02      OTHER DEFINITIONS.......................................................................       25
   SECTION 1.03      INCORPORATION BY REFERENCE OF TRUST INDENTURE ACT.......................................       26
   SECTION 1.04      RULES OF CONSTRUCTION...................................................................       26

ARTICLE 2 THE NOTES..........................................................................................       27
   SECTION 2.01      FORM AND DATING.........................................................................       27
   SECTION 2.02      EXECUTION AND AUTHENTICATION............................................................       27
   SECTION 2.03      REGISTRAR AND PAYING AGENT..............................................................       28
   SECTION 2.04      PAYING AGENT TO HOLD MONEY IN TRUST.....................................................       28
   SECTION 2.05      HOLDER LISTS............................................................................       29
   SECTION 2.06      TRANSFER AND EXCHANGE...................................................................       29
   SECTION 2.07      REPLACEMENT NOTES.......................................................................       33
   SECTION 2.08      OUTSTANDING NOTES.......................................................................       33
   SECTION 2.09      TREASURY NOTES..........................................................................       33
   SECTION 2.10      TEMPORARY NOTES.........................................................................       34
   SECTION 2.11      CANCELLATION............................................................................       34
   SECTION 2.12      DEFAULTED INTEREST......................................................................       34

ARTICLE 3 REDEMPTION AND PREPAYMENT..........................................................................       34
   SECTION 3.01      NOTICES TO TRUSTEE......................................................................       34
   SECTION 3.02      SELECTION OF NOTES TO BE REDEEMED.......................................................       35
   SECTION 3.03      NOTICE OF REDEMPTION....................................................................       35
   SECTION 3.04      EFFECT OF NOTICE OF REDEMPTION..........................................................       36
   SECTION 3.05      DEPOSIT OF REDEMPTION PRICE.............................................................       36
   SECTION 3.06      NOTES REDEEMED IN PART..................................................................       36
   SECTION 3.07      OPTIONAL REDEMPTION.....................................................................       36
   SECTION 3.08      MANDATORY REDEMPTION; OPEN MARKET PURCHASES.............................................       37
   SECTION 3.09      OFFER TO PURCHASE BY APPLICATION OF EXCESS PROCEEDS.....................................       38
   SECTION 3.10      CUSIP NUMBERS...........................................................................       40

ARTICLE 4 COVENANTS..........................................................................................       40
   SECTION 4.01      PAYMENT OF NOTES........................................................................       40
   SECTION 4.02      MAINTENANCE OF OFFICE OR AGENCY.........................................................       41
   SECTION 4.03      SEC REPORTS.............................................................................       41
   SECTION 4.04      COMPLIANCE CERTIFICATE..................................................................       42
   SECTION 4.05      TAXES...................................................................................       42
   SECTION 4.06      STAY, EXTENSION AND USURY LAWS..........................................................       43
   SECTION 4.07      LIMITATION ON RESTRICTED PAYMENTS.......................................................       43
   SECTION 4.08      LIMITATION ON RESTRICTIONS ON DISTRIBUTIONS FROM RESTRICTED SUBSIDIARIES................       45
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
                                                                                                                   Page
<S>                                                                                                                <C>
   SECTION 4.09      LIMITATION ON INDEBTEDNESS..............................................................       47
   SECTION 4.10      LIMITATION ON SALES OF ASSETS AND SUBSIDIARY STOCK......................................       51
   SECTION 4.11      LIMITATIONS ON AFFILIATE TRANSACTIONS...................................................       52
   SECTION 4.12      LIMITATIONS ON LIENS....................................................................       53
   SECTION 4.13      LIMITATION OF BUSINESS ACTIVITIES.......................................................       54
   SECTION 4.14      CORPORATE EXISTENCE.....................................................................       54
   SECTION 4.15      OPTIONAL OFFER TO REPURCHASE NOTES......................................................       54
   SECTION 4.16      [INTENTIONALLY OMITTED].................................................................       56
   SECTION 4.17      LIMITATION ON THE SALE OR ISSUANCE OF CAPITAL STOCK OF RESTRICTED SUBSIDIARIES..........       56
   SECTION 4.18      FUTURE SUBSIDIARY GUARANTORS............................................................       56
   SECTION 4.19      ADDITIONAL AMOUNTS......................................................................       57

ARTICLE 5 SUCCESSORS.........................................................................................       59
   SECTION 5.01      MERGER AND CONSOLIDATION................................................................       59

ARTICLE 6 DEFAULTS AND REMEDIES..............................................................................       61
   SECTION 6.01      EVENTS OF DEFAULT.......................................................................       61
   SECTION 6.02      ACCELERATION............................................................................       63
   SECTION 6.03      OTHER REMEDIES..........................................................................       63
   SECTION 6.04      WAIVER OF PAST DEFAULTS.................................................................       63
   SECTION 6.05      CONTROL BY MAJORITY.....................................................................       64
   SECTION 6.06      LIMITATION ON SUITS.....................................................................       64
   SECTION 6.07      RIGHTS OF HOLDERS OF NOTES TO RECEIVE PAYMENT...........................................       64
   SECTION 6.08      COLLECTION SUIT BY TRUSTEE..............................................................       64
   SECTION 6.09      TRUSTEE MAY FILE PROOFS OF CLAIM........................................................       65
   SECTION 6.10      PRIORITIES..............................................................................       65
   SECTION 6.11      UNDERTAKING FOR COSTS...................................................................       66

ARTICLE 7 TRUSTEE............................................................................................       66
   SECTION 7.01      DUTIES OF TRUSTEE.......................................................................       66
   SECTION 7.02      RIGHTS OF TRUSTEE.......................................................................       67
   SECTION 7.03      INDIVIDUAL RIGHTS OF TRUSTEE............................................................       68
   SECTION 7.04      TRUSTEE'S DISCLAIMER....................................................................       68
   SECTION 7.05      NOTICE OF DEFAULTS......................................................................       68
   SECTION 7.06      REPORTS BY TRUSTEE TO HOLDERS OF THE NOTES..............................................       68
   SECTION 7.07      COMPENSATION AND INDEMNITY..............................................................       69
   SECTION 7.08      REPLACEMENT OF TRUSTEE..................................................................       70
   SECTION 7.09      SUCCESSOR TRUSTEE BY MERGER, ETC........................................................       71
   SECTION 7.10      ELIGIBILITY; DISQUALIFICATION...........................................................       71
   SECTION 7.11      PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY.......................................       71
   SECTION 7.12      APPOINTMENT OF CO-TRUSTEE...............................................................       71

ARTICLE 8 LEGAL DEFEASANCE AND COVENANT DEFEASANCE...........................................................       72
   SECTION 8.01      OPTION TO EFFECT LEGAL DEFEASANCE OR COVENANT DEFEASANCE................................       72
   SECTION 8.02      LEGAL DEFEASANCE AND DISCHARGE..........................................................       72
</TABLE>

                                       ii

<PAGE>

<TABLE>
<CAPTION>
                                                                                                                   Page
<S>                                                                                                                <C>
   SECTION 8.03      COVENANT DEFEASANCE.....................................................................       73
   SECTION 8.04      CONDITIONS TO LEGAL OR COVENANT DEFEASANCE..............................................       73
   SECTION 8.05      DEPOSITED MONEY AND GOVERNMENT SECURITIES TO BE HELD IN TRUST; OTHER MISCELLANEOUS
                        PROVISIONS...........................................................................       75
   SECTION 8.06      REPAYMENT TO COMPANY....................................................................       75
   SECTION 8.07      REINSTATEMENT...........................................................................       76

ARTICLE 9 AMENDMENT, SUPPLEMENT AND WAIVER...................................................................       76
   SECTION 9.01      WITHOUT CONSENT OF HOLDERS OF NOTES.....................................................       76
   SECTION 9.02      WITH CONSENT OF HOLDERS OF NOTES........................................................       77
   SECTION 9.03      COMPLIANCE WITH TRUST INDENTURE ACT.....................................................       78
   SECTION 9.04      REVOCATION AND EFFECT OF CONSENTS.......................................................       78
   SECTION 9.05      NOTATION ON OR EXCHANGE OF NOTES........................................................       79
   SECTION 9.06      TRUSTEE TO SIGN AMENDMENTS, ETC.........................................................       79

ARTICLE 10 SUBSIDIARY GUARANTEES.............................................................................       79
   SECTION 10.01     GUARANTEE...............................................................................       79
   SECTION 10.02     LIMITATION ON LIABILITY.................................................................       82
   SECTION 10.03     LIMITATION ON GUARANTOR LIABILITY.......................................................       82
   SECTION 10.04     EXECUTION AND DELIVERY OF SUBSIDIARY GUARANTEE..........................................       82
   SECTION 10.05     NO WAIVER...............................................................................       83
   SECTION 10.06     MODIFICATION............................................................................       83
   SECTION 10.07     GUARANTORS MAY CONSOLIDATE, ETC., ON CERTAIN TERMS......................................       83
   SECTION 10.08     RELEASES FOLLOWING SALE OF ASSETS.......................................................       84

ARTICLE 11 SATISFACTION AND DISCHARGE........................................................................       85
   SECTION 11.01     SATISFACTION AND DISCHARGE..............................................................       85
   SECTION 11.02     APPLICATION OF TRUST MONEY..............................................................       86

ARTICLE 12 MISCELLANEOUS.....................................................................................       86
   SECTION 12.01     TRUST INDENTURE ACT CONTROLS............................................................       86
   SECTION 12.02     NOTICES.................................................................................       86
   SECTION 12.03     COMMUNICATION BY HOLDERS OF NOTES WITH OTHER HOLDERS OF NOTES...........................       87
   SECTION 12.04     CERTIFICATE AND OPINION AS TO CONDITIONS PRECEDENT......................................       87
   SECTION 12.05     FORM OF DOCUMENTS DELIVERED TO A TRUSTEE................................................       88
   SECTION 12.06     STATEMENTS REQUIRED IN CERTIFICATE OR OPINION...........................................       88
   SECTION 12.07     RULES BY TRUSTEE AND AGENTS.............................................................       89
   SECTION 12.08     NO PERSONAL LIABILITY OF DIRECTORS, OFFICERS, EMPLOYEES AND STOCKHOLDERS................       89
   SECTION 12.09     GOVERNING LAW, SUBMISSION TO JURISDICTION AND WAIVER OF JURY TRIAL......................       89
   SECTION 12.10     NO ADVERSE INTERPRETATION OF OTHER AGREEMENTS...........................................       90
   SECTION 12.11     SUCCESSORS..............................................................................       90
   SECTION 12.12     SEVERABILITY............................................................................       90
   SECTION 12.13     COUNTERPART ORIGINALS...................................................................       90
   SECTION 12.14     TABLE OF CONTENTS, HEADINGS, ETC........................................................       90
</TABLE>

                                      iii

<PAGE>

<TABLE>
<CAPTION>
                                                                                                           Page
<S>                                                                                                        <C>
EXHIBITS

Exhibit A     FORM OF NOTE............................................................................     A-1
Exhibit B     FORM OF SUBSIDIARY GUARANTEE............................................................     B-1
Exhibit C     FORM OF SUPPLEMENTAL INDENTURE..........................................................     C-1
</TABLE>

                                       iv

<PAGE>

      INDENTURE, dated as of October 8, 2004, among Maxcom Telecomunicaciones,
S.A. de C.V., a sociedad anonima de capital variable organized under the laws of
Mexico (the "Company"), Corporativo en Telecomunicaciones, S.A. de C.V., a
sociedad anonima de capital variable organized under the laws of Mexico, Maxcom
Servicios Administrativos, S.A. de C.V., a sociedad anonima de capital variable
organized under the laws of Mexico, Maxcom USA, Inc., a Delaware corporation
(together with Corporativo en Telecomunicaciones, S.A. de C.V., and Maxcom
Servicios Administrativos, S.A. de C.V., the "Guarantors"), and The Bank of New
York, a New York banking corporation, as Trustee (the "Trustee").

      NOW, THEREFORE, in consideration of the premises set forth herein and
other good and valuable consideration, the sufficiency of which is acknowledged,
the Company, the Guarantors and the Trustee agree as follows for the benefit of
each other and for the equal and ratable benefit of the Holders of the Senior
Step-Up Notes due 2009 (the "Notes"):

                                   ARTICLE 1

                          Definitions and incorporation
                                  by reference

Section 1.01 Definitions.

      "Additional Assets" means any:

      (1)   property, plant, equipment, concessions, licenses, permits and
            leases used in a Related Business;

      (2)   the Capital Stock of a Person that becomes a Restricted Subsidiary
            as a result of the acquisition of such Capital Stock by the Company
            or another Restricted Subsidiary; or

      (3)   Capital Stock constituting a minority interest in any Person that at
            such time is a Restricted Subsidiary;

provided, however, that any such Restricted Subsidiary described in clauses (2)
or (3) above is primarily engaged in a Related Business.

      "Adjusted Net Assets" of a Guarantor at any date shall mean the amount by
which the fair value of the property and other assets of such Guarantor exceeds
the total amount of liabilities, including, without limitation, contingent
liabilities (after giving effect to all other fixed and contingent liabilities
incurred or assumed on such date), but excluding liabilities under the
Subsidiary Guarantee of such Guarantor.

      "Affiliate" of any specified Person means any other Person, directly or
indirectly, controlling or controlled by or under direct or indirect common
control with, such specified Person.

<PAGE>

      For the purposes of this definition, "control" when used with respect to
any Person means the power to direct the management and policies of such Person,
directly or indirectly, whether through the ownership of voting securities, by
contract or otherwise and the terms "controlling" and "controlled" have meanings
correlative to the foregoing. For purposes of Sections 4.07, 4.10 and 4.11
hereof only, "Affiliate" shall also mean any beneficial owner of Capital Stock
representing 5% or more of the total voting power of the Voting Stock (on a
fully diluted basis) of the Company or of rights or warrants to purchase such
Capital Stock (whether or not currently exercisable) and any Person who would be
an Affiliate of any such beneficial owner pursuant to the first sentence hereof.

      "Agent" means any Registrar, Paying Agent or co-registrar.

      "Applicable Procedures" means, with respect to any transfer or exchange of
or for beneficial interests in the Global Note, the rules and procedures of the
Depositary that apply to such transfer or exchange.

      "Asset Disposition" means any sale, lease, transfer or other disposition
(or series of related sales, leases, transfers or dispositions) by the Company
or any Restricted Subsidiary, including any disposition by means of a merger,
consolidation or similar transaction (each referred to for the purposes of this
definition as a "disposition") (other than any Exit Transaction which complies
with Section 5.01), of:

      (1)   any shares of Capital Stock of a Restricted Subsidiary (other than
            directors' qualifying shares or shares required by applicable law to
            be held by a Person other than the Company or a Restricted
            Subsidiary);

      (2)   all or substantially all the assets of any division or line of
            business of the Company or any Restricted Subsidiary; or

      (3)   any other assets of the Company or any Restricted Subsidiary outside
            of the ordinary course of business of the Company or such Restricted
            Subsidiary

other than, in the case of clauses (1), (2) and (3)

            (A)   a disposition by a Restricted Subsidiary to the Company or by
                  the Company or a Restricted Subsidiary to a Wholly Owned
                  Subsidiary;

            (B)   for purposes of Section 4.10 hereof only, any disposition (i)
                  that constitutes a Restricted Payment permitted by Section
                  4.07 hereof, (ii) of cash or (iii) of Temporary Cash
                  Investments;

            (C)   a disposition of assets with a fair market value of less than
                  U.S.$100,000;

            (D)   exchange of telecommunications assets where the Fair Market
                  Value of the telecommunications assets received is at least
                  equal to the Fair Market Value of the telecommunications
                  assets disposed of or if less, the difference is received in
                  cash, and such cash is Net Available Cash;

                                       2

<PAGE>

            (E)   dispositions of obsolete, worn-out, damaged or otherwise
                  unsuitable or unnecessary equipment or other obsolete assets
                  in the ordinary course of business;

            (F)   dispositions of capacity and rights of use in the Company's
                  network in the ordinary course of business; and

            (G)   the disposition, sale, conveyance or other transfer of assets
                  of the Company and its Restricted Subsidiaries (including,
                  without limitation, accounts receivable and related assets
                  customarily transferred in an asset securitization transaction
                  involving accounts receivable) to a Qualified Subsidiary or by
                  a Qualified Subsidiary, in connection with a Qualified
                  Securitization Transaction.

      "Attributable Debt" in respect of a Sale/Leaseback Transaction means, as
at the time of determination, the present value (discounted at the interest rate
borne by the Notes, compounded annually) of the total obligations of the lessee
for rental payments during the remaining term of the lease included in such
Sale/Leaseback Transaction (including any period for which such lease has been
extended).

      "Average Life" means, as of the date of determination, with respect to any
Indebtedness, the quotient obtained by dividing:

      (1)   the sum of the products of numbers of years from the date of
            determination to the dates of each successive scheduled principal
            payment of or redemption or similar payment with respect to such
            Indebtedness multiplied by the amount of such payment by

      (2)   the sum of all such payments.

      "Bankruptcy Law" means Title 11, U.S. Code or any similar federal or state
law for the relief of debtors or the administration or liquidation of debtors'
estates for the benefit of their creditors, and the Ley de Concursos
Mercantiles, or any similar federal or state law for the relief of debtors or
the administration or liquidation of debtors' estates for the benefit of their
creditors.

      "Board of Directors" means the Board of Directors of the Company or any
committee thereof duly authorized to act on behalf of such Board.

      "Business Day" means a day other than a Saturday, Sunday or other day on
which commercial banking institutions are authorized or required by law to close
in Mexico or New York City.

      "Capital Lease Obligation" means an obligation that is required to be
classified and accounted for as a capital lease for financial reporting purposes
in accordance with GAAP, and the amount of Indebtedness represented by such
obligation shall be the capitalized amount of such obligation determined in
accordance with GAAP; and the Stated Maturity thereof shall be the date of the
last payment of rent or any other amount due under such lease prior to the first
date upon which such lease may be terminated by the lessee without payment of a
penalty.

                                       3

<PAGE>

      "Capital Stock" of any Person means any and all shares, interests, rights
to purchase, warrants, options, participations or other equivalents of or
interests in (however designated) equity of such Person, including any Preferred
Stock, but excluding any debt securities convertible into such equity.

      "Code" means the Internal Revenue Code of 1986, as amended.

      "Company" means Maxcom Telecomunicaciones, S.A. de C.V., and any and all
successors thereto.

      "Consolidated Cash Flow" for any period means the sum of Consolidated Net
Income, plus the following to the extent deducted in calculating such
Consolidated Net Income:

      (1)   all income and asset tax expense of the Company and its consolidated
            Restricted Subsidiaries;

      (2)   Consolidated Interest Expense;

      (3)   depreciation and amortization expense of the Company and its
            consolidated Restricted Subsidiaries (excluding amortization expense
            attributable to an item that was prepaid in cash in a prior period,
            other than the Company's preoperating expenses that were capitalized
            in accordance with GAAP); and

      (4)   all other non-cash charges of the Company and its consolidated
            Restricted Subsidiaries (excluding any such non-cash charge to the
            extent that it represents an accrual of or reserve for cash
            expenditures in any future period);

in each case for such period; minus the sum of the following to the extent it
increases Consolidated Net Income:

      (1)   interest income; and

      (2)   all non-cash items of the Company and its consolidated Restricted
            Subsidiaries (excluding any such non-cash item to the extent that it
            results in the receipt of cash payments in any future period).

      Notwithstanding the foregoing, the provision for taxes based on the income
or profits of, and the depreciation and amortization and non-cash charges of a
Restricted Subsidiary shall be added to Consolidated Net Income to compute
Consolidated Cash Flow only to the extent (and in the same proportion) that the
net income of such Restricted Subsidiary was included in calculating
Consolidated Net Income and only if a corresponding amount would be permitted at
the date of determination to be dividended to the Company by such Restricted
Subsidiary without prior approval (that has not been obtained), pursuant to the
terms of its charter and all agreements, instruments, judgments, decrees,
orders, statutes, rules and governmental regulations applicable to such
Restricted Subsidiary or its stockholders.

      "Consolidated Interest Expense" means, for any period, the total interest
expense of the Company and its consolidated Restricted Subsidiaries, plus, to
the extent not included in such

                                       4

<PAGE>

total interest expense, and to the extent Incurred by the Company or its
Restricted Subsidiaries, without duplication:

      (1)   interest expense attributable to capital leases and the interest
            expense attributable to leases constituting part of a Sale/Leaseback
            Transaction;

      (2)   amortization of debt discount and debt issuance cost;

      (3)   capitalized interest;

      (4)   non-cash interest expenses;

      (5)   commissions, discounts and other fees and charges owed with respect
            to letters of credit and bankers' acceptance financing;

      (6)   net payments pursuant to Hedging Obligations;

      (7)   the product of (a) all dividends, whether paid or accrued and
            whether or not in cash, on any series of Preferred Stock of such
            Person or any of its Subsidiaries, other than dividends on Equity
            Interests payable solely in Equity Interests of the Company (other
            than Disqualified Stock) or to the Company or a Subsidiary of the
            Company or any liquidation preference amounts accruing or accreting
            under the terms of the New Preferred Shares, times (b) a fraction,
            the numerator of which is one and the denominator of which is one
            minus the then current combined federal, state and local statutory
            tax rate of such Person, expressed as a decimal, in each case, on a
            consolidated basis and in accordance with GAAP;

      (8)   interest incurred in connection with Investments in discontinued
            operations;

      (9)   interest accruing on any Indebtedness of any other Person to the
            extent such Indebtedness is Guaranteed by (or secured by the assets
            of) the Company or any Restricted Subsidiary; and

      (10)  the cash contributions to any employee stock ownership plan or
            similar trust to the extent such contributions are used by such plan
            or trust to pay interest or fees to any Person (other than the
            Company) in connection with Indebtedness Incurred by such plan or
            trust.

      "Consolidated Leverage Ratio" as of any date of determination means the
ratio of (x) the aggregate amount of Indebtedness of the Company and its
Restricted Subsidiaries as of such date of determination to (y) Consolidated
Cash Flow for the most recent fiscal quarter ending at least 45 days prior to
such date of determination (the "Reference Period") multiplied by four,
provided, however, that:

      (1)   if the transaction giving rise to the need to calculate the
            Consolidated Leverage Ratio is an Incurrence of Indebtedness, the
            amount of such Indebtedness shall be calculated after giving effect
            on a pro forma basis to such Indebtedness;

                                       5

<PAGE>

      (2)   if the Company or any Restricted Subsidiary has repaid, repurchased,
            defeased or otherwise discharged any Indebtedness that was
            outstanding as of the end of the Reference Period or if any
            Indebtedness is to be repaid, repurchased, defeased or otherwise
            discharged on the date of the transaction giving rise to the need to
            calculate the Consolidated Leverage Ratio (other than, in each case,
            Indebtedness Incurred under any revolving credit agreement), the
            aggregate amount of Indebtedness shall be calculated after giving
            effect on a pro forma basis to the repayment, repurchase, defeasance
            or discharge of Indebtedness and Consolidated Cash Flow shall be
            calculated as if the Company or such Restricted Subsidiary had not
            earned the interest income, if any, actually earned during the
            Reference Period in respect of cash or Temporary Cash Investments
            used to repay, repurchase, defease or otherwise discharge such
            Indebtedness;

      (3)   if since the beginning of the Reference Period the Company or any
            Restricted Subsidiary shall have made any Asset Disposition, the
            Consolidated Cash Flow for the Reference Period shall be reduced by
            an amount equal to the Consolidated Cash Flow (if positive) directly
            attributable to the assets which are the subject of such Asset
            Disposition for the Reference Period or increased by an amount equal
            to the Consolidated Cash Flow (if negative) directly attributable
            thereto for the Reference Period;

      (4)   if since the beginning of the Reference Period the Company or any
            Restricted Subsidiary (by merger or otherwise) shall have made an
            Investment in any Restricted Subsidiary (or any Person which becomes
            a Restricted Subsidiary) or an acquisition of assets which
            constitutes all or substantially all of an operating unit of a
            business, Consolidated Cash Flow for the Reference Period shall be
            calculated after giving pro forma effect thereto (including the
            Incurrence of any Indebtedness) as if such Investment or acquisition
            occurred on the first day of the Reference Period; and

      (5)   if since the beginning of the Reference Period any Person (that
            subsequently became a Restricted Subsidiary or was merged with or
            into the Company or any Restricted Subsidiary since the beginning of
            such Reference Period) shall have made any Asset Disposition, any
            Investment or acquisition of assets that would have required an
            adjustment pursuant to clause (3) or (4) above if made by the
            Company or a Restricted Subsidiary during the Reference Period,
            Consolidated Cash Flow for the Reference Period shall be calculated
            after giving pro forma effect thereto as if such Asset Disposition,
            Investment or acquisition occurred on the first day of the Reference
            Period.

      "Consolidated Net Income" means, for any period, the net income of the
Company and its consolidated Subsidiaries; provided, however, that there shall
not be included in such Consolidated Net Income:

      (1)   any net income of any Person (other than the Company) if such Person
            is not a Restricted Subsidiary, except that:

                                       6

<PAGE>

            (A)   subject to the exclusion contained in clause (4) below, the
                  Company's equity in the net income of any such Person for such
                  period shall be included in such Consolidated Net Income up to
                  the aggregate amount of cash actually distributed by such
                  Person during such period to the Company or a Restricted
                  Subsidiary as a dividend or other distribution (subject, in
                  the case of a dividend or other distribution paid to a
                  Restricted Subsidiary, to the limitations contained in clause
                  (3) below); and

            (B)   the Company's equity in a net loss of any such Person for such
                  period shall be included in determining such Consolidated Net
                  Income;

      (2)   any net income (or loss) of any Person acquired by the Company or a
            Subsidiary in a pooling of interests transaction for any period
            prior to the date of such acquisition;

      (3)   any net income of any Restricted Subsidiary if such Restricted
            Subsidiary is subject to restrictions, directly or indirectly, on
            the payment of dividends or the making of distributions by such
            Restricted Subsidiary, directly or indirectly, to the Company,
            except that:

            (A)   subject to the exclusion contained in clause (4) below, the
                  Company's equity in the net income of any such Restricted
                  Subsidiary for such period shall be included in such
                  Consolidated Net Income up to the aggregate amount of cash
                  actually distributed by such Restricted Subsidiary during such
                  period to the Company or another Restricted Subsidiary as a
                  dividend or other distribution (subject, in the case of a
                  dividend or other distribution paid to another Restricted
                  Subsidiary, to the limitation contained in this clause); and

            (B)   the Company's equity in a net loss of any such Restricted
                  Subsidiary for such period shall be included in determining
                  such Consolidated Net Income;

      (4)   any gain (but not loss) realized upon the sale or other disposition
            of any assets of the Company, its consolidated Subsidiaries or any
            other Person (including pursuant to any sale-and-leaseback
            arrangement) which is not sold or otherwise disposed of in the
            ordinary course of business and any gain (but not loss) realized
            upon the sale or other disposition of any Capital Stock of any
            Person;

      (5)   extraordinary gains or losses; and

      (6)   the cumulative effect of a change in accounting principles.

      "Consolidated Net Worth" means the total of the amounts shown on the
balance sheet of the Company and its consolidated Subsidiaries, determined on a
consolidated basis in accordance with GAAP, as of the end of the most recent
fiscal quarter of the Company ending at least 45 days prior to the taking of any
action for the purpose of which the determination is being made, as the sum of:

                                       7

<PAGE>

      (1)   the par or stated value of all outstanding Capital Stock of the
            Company plus

      (2)   paid-in capital or capital surplus relating to such Capital Stock
            plus

      (3)   any retained earnings or earned surplus

less (A) any accumulated deficit and (B) any amounts attributable to
Disqualified Stock.

      "Corporate Trust Office of the Trustee" means the principal office of the
Trustee at which at any time its corporate trust business shall be administered,
which office as of the date hereof is located at 101 Barclay Street, Floor 21W,
New York, New York 10286, Attention: Corporate Trust Administration, or such
other address as the Trustee may designate from time to time by notice to the
Holders and the Company, or the principal corporate trust office of any
successor Trustee (or such other address as a successor Trustee may designate
from time to time by notice to the Holders and the Company).

      "Currency Agreement" means in respect of a Person any foreign exchange
contract, currency swap agreement or other similar agreement designed to protect
such Person against fluctuations in currency values.

      "Custodian" means the Trustee, as custodian with respect to the Notes in
global form, or any successor entity thereto.

      "Default" means any event that is, or after notice or passage of time or
both would be, an Event of Default.

      "Definitive Note" means a certificated Note registered in the name of the
Holder thereof and issued in accordance with Section 2.06 hereof, substantially
in the form of Exhibit A hereto except that such Note shall not bear the Global
Note Legend and shall not have the "Schedule of Exchanges of Interests in the
Global Note" attached thereto.

      "Depositary" means, with respect to the Notes issuable or issued in whole
or in part in global form, the Person specified in Section 2.03 hereof as the
Depositary with respect to the Notes, and any and all successors thereto
appointed as depositary hereunder and having become such pursuant to the
applicable provision of this Indenture.

      "Disqualified Stock" means, with respect to any Person, any Capital Stock
which by its terms (or by the terms of any security into which it is convertible
or for which it is exchangeable at the option of the holder) or upon the
happening of any event:

      (1)   matures or is mandatorily redeemable pursuant to a sinking fund
            obligation or otherwise;

      (2)   is convertible or exchangeable at the option of the holder for
            Indebtedness or Disqualified Stock; or

      (3)   is mandatorily redeemable or must be purchased upon the occurrence
            of certain events or otherwise, in whole or in part;

                                       8

<PAGE>

in each case on or prior to the first anniversary of the Stated Maturity of the
Notes; provided, however, that the New Preferred Shares shall not be deemed
Disqualified Stock; and provided further that any Capital Stock that would not
constitute Disqualified Stock but for provisions thereof giving holders thereof
the right to require such Person to purchase or redeem such Capital Stock upon
the occurrence of an "asset sale" or "change of control" occurring prior to the
first anniversary of the Stated Maturity of the Notes shall not constitute
Disqualified Stock if:

      (1)   the "asset sale" or "change of control" provisions applicable to
            such Capital Stock are not more favorable to the holders of such
            Capital Stock than the terms applicable to the Notes and described
            under Sections 4.10, 4.15 and 5.01(a) hereof; and

      (2)   any such requirement only becomes operative after compliance with
            such terms applicable to the Notes, including the purchase of any
            Notes tendered pursuant thereto.

      "Equity Interests" means Capital Stock and all warrants, options or other
rights to acquire Capital Stock (but excluding any debt security that is
convertible into, or exchangeable for, Capital Stock).

      "Exchange Act" means the Securities Exchange Act of 1934, as amended.

      "Fair Market Value" means, with respect to any asset or property
(including Capital Stock), the price that could be negotiated in an arm's-length
free market transaction, for cash, between a willing seller and a willing buyer,
neither of whom is under pressure or compulsion to complete the transaction.
Fair Market Value shall be determined by the Board of Directors of the Company
acting in good faith and shall be evidenced by a resolution of the Board of
Directors of the Company delivered to the Trustee.

      "Fixed Charge Coverage Ratio" as of any date of determination means with
respect to any specified Person for any period, the ratio of the Consolidated
Cash Flow to Consolidated Interest Expense of such Person for the most recent
fiscal quarter ending at least 45 days prior to the date of determination. In
the event that the specified Person or any of its Subsidiaries incurs, assumes,
Guarantees, repays, repurchases or redeems any Indebtedness (other than ordinary
working capital borrowings) or issues, repurchases or redeems preferred stock
subsequent to the commencement of the period for which the Fixed Charge Coverage
Ratio is being calculated and on or prior to the date on which the event for
which the calculation of the Fixed Charge Coverage Ratio is made (the
"Calculation Date"), then the Fixed Charge Coverage Ratio will be calculated
giving pro forma effect to such incurrence, assumption, Guarantee, repayment,
repurchase or redemption of Indebtedness, or such issuance, repurchase or
redemption of preferred stock, and the use of the proceeds therefrom as if the
same had occurred at the beginning of the applicable reference period.

      In addition, for purposes of calculating the Fixed Charge Coverage Ratio:

      (1)   acquisitions that have been made by the specified Person or any of
            its Subsidiaries, including through mergers or consolidations and
            including any related financing transactions, during the reference
            period or subsequent to such

                                       9

<PAGE>

            reference period and on or prior to the Calculation Date will be
            given pro forma effect as if they had occurred on the first day of
            the reference period and Consolidated Cash Flow for such reference
            period will be calculated on a pro forma basis in accordance with
            Regulation S-X under the Securities Act, but without giving effect
            to clause (2) of the proviso set forth in the definition of
            Consolidated Net Income;

      (2)   the Consolidated Cash Flow attributable to discontinued operations,
            as determined in accordance with GAAP, and operations or businesses
            disposed of prior to the Calculation Date, will be excluded; and

      (3)   the Consolidated Interest Expense attributable to discontinued
            operations, as determined in accordance with GAAP, and operations or
            businesses disposed of prior to the Calculation Date, will be
            excluded, but only to the extent that the obligations giving rise to
            such Consolidated Interest Expense will not be obligations of the
            specified Person or any of its Subsidiaries following the
            Calculation Date.

      "GAAP" means generally accepted accounting principles in Mexico, as
amended from time to time.

      "Global Note" means a permanent global note substantially in the form of
Exhibit A attached hereto that bears the Global Note Legend and that has the
"Schedule of Exchanges of Interests in the Global Note" attached thereto, and
that is deposited with or on behalf of and registered in the name of the
Depositary, representing the Notes.

      "Global Note Legend" means the legend set forth in Section 2.06(f)(i),
which is required to be placed on all Global Notes issued under this Indenture.

      "Government Securities" means direct obligations of, or obligations
guaranteed by, the United States of America, and the payment for which the
United States pledges its full faith and credit.

      "Guarantee" means any obligation, contingent or otherwise, of any Person
directly or indirectly guaranteeing any Indebtedness of any Person and any
obligation, direct or indirect, contingent or otherwise, of such Person:

      (1)   to purchase or pay (or advance or supply funds for the purchase or
            payment of) such Indebtedness of such Person (whether arising by
            virtue of partnership arrangements, or by agreements to keep-well,
            to purchase assets, goods, securities or services, to take-or-pay or
            to maintain financial statement conditions or otherwise); or

      (2)   entered into for the purpose of assuring in any other manner the
            obligee of such Indebtedness of the payment thereof or to protect
            such obligee against loss in respect thereof (in whole or in part);

                                       10

<PAGE>

provided, however, that the term "Guarantee" shall not include endorsements for
collection or deposit in the ordinary course of business. The term "Guarantee"
used as a verb has a corresponding meaning.

      "Guarantors" means each of:

      (1)   Corporativo en Telecomunicaciones, S.A. de C.V.;

      (2)   Maxcom Servicios Administrativos, S.A. de C.V.;

      (3)   Maxcom USA, Inc.; and

      (4)   any other subsidiary that executes a Subsidiary Guarantee in
            accordance with the provisions of this Indenture;

and their respective successors and assigns.

      "Hedging Obligations" of any Person means the obligations of such Person
pursuant to any Interest Rate Agreement or Currency Agreement.

      "Holder" or "Noteholder" means the Person in whose name a Note is
registered on the Registrar's books.

      "Incur" means issue, assume, Guarantee, incur or otherwise become liable
for; provided, however, that any Indebtedness or Capital Stock of a Person
existing at the time such Person becomes a Restricted Subsidiary (whether by
merger, consolidation, acquisition or otherwise) shall be deemed to be Incurred
by such Person at the time it becomes a Restricted Subsidiary. The term
"Incurrence" when used as a noun shall have a correlative meaning. The accretion
of principal of a non-interest bearing or other discount security shall be
deemed the Incurrence of Indebtedness.

      "Indebtedness" means, with respect to any Person on any date of
determination (without duplication):

      (1)   the principal in respect of (A) indebtedness of such Person for
            money borrowed and (B) indebtedness evidenced by notes, debentures,
            bonds or other similar instruments for the payment of which such
            Person is responsible or liable, including, in each case, any
            premium on such indebtedness to the extent such premium has become
            due and payable;

      (2)   all Capital Lease Obligations of such Person and all Attributable
            Debt in respect of Sale/Leaseback Transactions entered into by such
            Person;

      (3)   all obligations of such Person issued or assumed as the deferred
            purchase price of property, all conditional sale obligations of such
            Person and all obligations of such Person under any title retention
            agreement (but excluding trade accounts payable arising in the
            ordinary course of business);

                                       11

<PAGE>

      (4)   all obligations of such Person for the reimbursement of any obligor
            on any letter of credit, banker's acceptance or similar credit
            transaction (other than obligations with respect to letters of
            credit securing obligations (other than obligations described in
            clauses (1) through (3) above) entered into in the ordinary course
            of business of such Person to the extent such letters of credit are
            not drawn upon or, if and to the extent drawn upon, such drawing is
            reimbursed no later than the tenth Business Day following payment on
            the letter of credit);

      (5)   the amount of all obligations of such Person with respect to the
            redemption, repayment or other repurchase of any Disqualified Stock
            of such Person or, with respect to any Preferred Stock of any
            Subsidiary of such Person, the principal amount of such Preferred
            Stock to be determined in accordance with this Indenture (but
            excluding, in each case, any accrued dividends);

      (6)   all obligations of the type referred to in clauses (1) through (5)
            of other Persons and all dividends of other Persons for the payment
            of which, in either case, such Person is responsible or liable,
            directly or indirectly, as obligor, guarantor or otherwise,
            including by means of any Guarantee;

      (7)   all obligations of the type referred to in clauses (1) through (6)
            of other Persons secured by any Lien on any property or asset of
            such Person (whether or not such obligation is assumed by such
            Person), the amount of such obligation being deemed to be the lesser
            of the value of such property or assets and the amount of the
            obligation so secured; and

      (8)   to the extent not otherwise included in this definition, Hedging
            Obligations of such Person.

      The amount of Indebtedness of any Person at any date shall be the
outstanding balance at such date of all unconditional obligations as described
above and the maximum liability, upon the occurrence of the contingency giving
rise to the obligation, of any contingent obligations at such date.

      "Indenture" means this Indenture, as amended or supplemented from time to
time.

      "Indirect Participant" means a Person who holds a beneficial interest in
the Global Note through a Participant.

      "Interest Rate Agreement" means in respect of a Person any interest rate
swap agreement, interest rate cap agreement or other financial agreement or
arrangement designed to protect such Person against fluctuations in interest
rates.

      "Investment" in any Person means any direct or indirect advance (other
than advances to customers in the ordinary course of business that are recorded
as accounts receivable on the balance sheet of the lender), loan or other
extensions of credit (including by way of Guarantee or similar arrangement) or
capital contribution to (by means of any transfer of cash or other property to
others or any payment for property or services for the account or use of
others), or

                                       12

<PAGE>

any purchase or acquisition of Capital Stock, Indebtedness or other similar
instruments issued by such Person.

      For purposes of the definition of "Unrestricted Subsidiary," the
definition of "Restricted Payment" and Section 4.07 hereof:

      (1)   "Investment" shall include the portion (proportionate to the
            Company's equity interest in such Subsidiary) of the fair market
            value of the net assets of any Subsidiary of the Company at the time
            that such Subsidiary is designated an Unrestricted Subsidiary;
            provided, however, that upon a redesignation of such Subsidiary as a
            Restricted Subsidiary, the Company shall be deemed to continue to
            have a permanent "Investment" in an Unrestricted Subsidiary equal to
            an amount (if positive) equal to (A) the Company's "Investment" in
            such Subsidiary at the time of such redesignation less (B) the
            portion (proportionate to the Company's equity interest in such
            Subsidiary) of the fair market value of the net assets of such
            Subsidiary at the time of such redesignation; and

      (2)   any property transferred to or from an Unrestricted Subsidiary shall
            be valued at its fair market value at the time of such transfer, in
            each case as determined in good faith by the Board of Directors.

      "Issue Date" means the date on which the Notes are originally issued.

      "Lien" means any mortgage, pledge, security interest, encumbrance, lien or
charge of any kind (including any conditional sale or other title retention
agreement or lease in the nature thereof).

      "N-2 Shares" means any of the Series N-2 Convertible Preferred Shares of
the Company together with any ordinary participation certificates (certificados
participacion ordinarios) through which such securities may be held from time to
time.

      "Net Available Cash" from an Asset Disposition means cash payments
received therefrom (including any cash payments received by way of deferred
payment of principal pursuant to a Note or installment receivable or otherwise
and proceeds from the sale or other disposition of any securities received as
consideration, but only as and when received, but excluding any other
consideration received in the form of assumption by the acquiring Person of
Indebtedness or other obligations relating to such properties or assets or
received in any other noncash form), in each case net of:

      (1)   all legal, title and recording tax expenses, commissions and other
            fees and expenses incurred, and all Federal, state, provincial,
            foreign and local taxes required to be accrued as a liability under
            GAAP, as a consequence of such Asset Disposition;

      (2)   all payments made on any Indebtedness which is secured by any assets
            subject to such Asset Disposition, in accordance with the terms of
            any Lien upon or other security agreement of any kind with respect
            to such assets, or which must by its

                                       13

<PAGE>

            terms, or in order to obtain a necessary consent to such Asset
            Disposition, or by applicable law, be repaid out of the proceeds
            from such Asset Disposition;

      (3)   all distributions and other payments required to be made to minority
            interest holders in Restricted Subsidiaries as a result of such
            Asset Disposition; and

      (4)   the deduction of appropriate amounts provided by the seller as a
            reserve, in accordance with GAAP, against any liabilities associated
            with the property or other assets disposed in such Asset Disposition
            and retained by the Company or any Restricted Subsidiary after such
            Asset Disposition.

      "Net Cash Proceeds," with respect to any issuance or sale of Capital
Stock, means the cash proceeds of such issuance or sale net of attorneys' fees,
accountants' fees, underwriters' or placement agents' fees, discounts or
commissions and brokerage, consultant and other fees actually incurred in
connection with such issuance or sale and net of taxes paid or payable as a
result thereof.

      "New Preferred Shares" means the Series A-1 Convertible Preferred Shares,
Series B-1 Convertible Preferred Shares, Series N-1 Convertible Preferred Shares
and N-2 Shares of the Company, in each case with such rights and designations
set forth in the by-laws (estatutos) of the Company in effect on the Issue Date.

      "Notes" has the meaning assigned to it in the preamble to this Indenture.

      "Obligations" means any principal, interest, penalties, fees,
indemnifications, reimbursements, damages and other liabilities payable under
the documentation governing any Indebtedness.

      "Offering Circular" means the offering circular, dated September 8, 2004,
as supplemented and amended from time to time prior to the Issue Date, pursuant
to which, among other things, the Company offered the Notes.

      "Officer" means, with respect to any Person, the Chairman of the Board,
the Chief Executive Officer, the President, the Chief Operating Officer, the
Chief Financial Officer, the Treasurer, any Assistant Treasurer, the Controller,
the Secretary or any Vice-President of such Person.

      "Officers' Certificate" means a certificate signed on behalf of the
Company by two Officers of the Company, one of whom must be the principal
executive officer, the principal financial officer, the treasurer or the
principal accounting officer of the Company, that meets the requirements of
Section 12.04(a) hereof.

      "Opinion of Counsel" means an opinion from legal counsel who is reasonably
acceptable to the Trustee, that meets the requirements of Section 12.04(b)
hereof. The counsel may be an employee of or counsel to the Company, any
Subsidiary of the Company or the Trustee.

      "Participant" means, with respect to the Depositary, a Person who has an
account with the Depositary.

                                       14

<PAGE>

      "Permitted Investment" means an Investment by the Company or any
Restricted Subsidiary in:

      (1)   the Company, a Restricted Subsidiary or a Person that will, upon the
            making of such Investment, become a Restricted Subsidiary; provided,
            however, that the primary business of such Restricted Subsidiary is
            a Related Business;

      (2)   another Person if as a result of such Investment such other Person
            is merged or consolidated with or into, or transfers or conveys all
            or substantially all its assets to, the Company or a Restricted
            Subsidiary; provided, however, that such Person's primary business
            is a Related Business;

      (3)   cash and Temporary Cash Investments;

      (4)   receivables owing to the Company or any Restricted Subsidiary if
            created or acquired in the ordinary course of business and payable
            or dischargeable in accordance with customary trade terms; provided,
            however, that such trade terms may include such concessionary trade
            terms as the Company or any such Restricted Subsidiary deems
            reasonable under the circumstances;

      (5)   payroll, travel and similar advances to cover matters that are
            expected at the time of such advances ultimately to be treated as
            expenses for accounting purposes and that are made in the ordinary
            course of business;

      (6)   loans or advances to employees made in the ordinary course of
            business consistent with past practices of the Company or such
            Restricted Subsidiary;

      (7)   stock, obligations or securities received in settlement of debts
            created in the ordinary course of business and owing to the Company
            or any Restricted Subsidiary or in satisfaction of judgments;

      (8)   any Person to the extent such Investment represents the non-cash
            portion of the consideration received for an Asset Disposition as
            permitted pursuant to Section 4.10 hereof;

      (9)   any Hedging Obligations permitted to be Incurred under Section 4.09
            hereof;

      (10)  other Investments in an aggregate amount not to exceed U.S.$25.0
            million at any one time outstanding thereafter, so long as in each
            case such Investments are made in a Telecommunications Business; and

      (11)  a Qualified Subsidiary or any Investment by a Qualified Subsidiary
            in any other person, in each case, in connection with a Qualified
            Securitization Transaction, provided, that the Investment in any
            person is in the form of a Purchase Money Note, an equity interest,
            a beneficial interest in a Mexican security administration trust or
            an interest in assets of the Company or a Restricted Subsidiary
            (including, without limitation, accounts receivable or contracts
            receivable generated by the

                                       15

<PAGE>

            Company or a Restricted Subsidiary) and transferred to any person in
            connection with a Qualified Securitization Transaction or any person
            owning those assets.

      "Permitted Liens" means, with respect to any Person:

      (1)   pledges or deposits by such Person under worker's compensation laws,
            unemployment insurance laws or similar legislation, or good faith
            deposits in connection with bids, tenders, contracts (other than for
            the payment of Indebtedness) or leases to which such Person is a
            party, or deposits to secure public or statutory obligations of such
            Person or deposits of cash or United States government bonds to
            secure surety or appeal bonds to which such Person is a party, or
            deposits as security for contested taxes or import duties or for the
            payment of rent, in each case Incurred in the ordinary course of
            business;

      (2)   Liens imposed by law, such as carriers', warehousemen's and
            mechanics' Liens, in each case for sums not yet due or being
            contested in good faith by appropriate proceedings or other Liens
            arising out of judgments or awards against such Person with respect
            to which such Person shall then be proceeding with an appeal or
            other proceedings for review and Liens arising solely by virtue of
            any statutory or common law provision relating to banker's Liens,
            rights of set-off or similar rights and remedies as to deposit
            accounts or other funds maintained with a creditor depository
            institution; provided, however, that (A) such deposit account is not
            a dedicated cash collateral account and is not subject to
            restrictions against access by the Company in excess of those set
            forth by regulations promulgated by the Federal Reserve Board and
            (B) such deposit account is not intended by the Company or any
            Restricted Subsidiary to provide collateral to the depository
            institution;

      (3)   Liens for taxes not yet subject to penalties for non-payment or
            which are being contested in good faith and by appropriate
            proceedings;

      (4)   Liens in favor of issuers of surety bonds or letters of credit
            issued pursuant to the request of and for the account of such Person
            in the ordinary course of its business; provided, however, that such
            letters of credit do not constitute Indebtedness;

      (5)   survey exceptions, encumbrances, easements or reservations of, or
            rights of others for, licenses, rights-of-way, sewers, electric
            lines, telegraph and telephone lines and other similar purposes, or
            zoning or other restrictions as to the use of real property or Liens
            incidental to the conduct of the business of such Person or to the
            ownership of its properties which were not Incurred in connection
            with Indebtedness and which do not in the aggregate materially
            adversely affect the value of said properties or materially impair
            their use in the operation of the business of such Person;

      (6)   Liens securing Indebtedness Incurred to finance the construction,
            purchase or lease of, or repairs, improvements or additions to,
            property, plant or equipment of

                                       16

<PAGE>

            such Person; provided, however, that the Lien may not extend to any
            other property owned by such Person or any of its Restricted
            Subsidiaries at the time the Lien is Incurred (other than assets and
            property affixed or appurtenant thereto), and the Indebtedness
            (other than any interest thereon) secured by the Lien may not be
            Incurred more than 180 days after the later of the acquisition,
            completion of construction, repair, improvement, addition or
            commencement of full operation of the property subject to the Lien;

      (7)   Liens to secure Indebtedness permitted under the provisions
            described in clause (b) (1) of Section 4.09 hereof;

      (8)   Liens existing on the Issue Date;

      (9)   Liens on property or shares of Capital Stock of another Person at
            the time such other Person becomes a Subsidiary of such Person;
            provided, however, that the Liens may not extend to any other
            property owned by such Person or any of its Restricted Subsidiaries
            (other than assets and property affixed or appurtenant thereto);

      (10)  Liens on property at the time such Person or any of its Subsidiaries
            acquires the property, including any acquisition by means of a
            merger or consolidation with or into such Person or a Subsidiary of
            such Person; provided, however, that the Liens may not extend to any
            other property owned by such Person or any of its Restricted
            Subsidiaries (other than assets and property affixed or appurtenant
            thereto);

      (11)  Liens securing Indebtedness or other obligations of a Subsidiary of
            such Person owing to such Person or a wholly-owned Subsidiary of
            such Person;

      (12)  Liens securing Hedging Obligations so long as such Hedging
            Obligations relate to Indebtedness that is, and is permitted to be
            under this Indenture, secured by a Lien on the same property
            securing such Hedging Obligations;

      (13)  Liens to secure any Refinancing (or successive Refinancings) as a
            whole, or in part, of any Indebtedness secured by any Lien referred
            to in clauses (6), (8), (9), (10), (14) or (15); provided, however,
            that:

            (A)   such new Lien shall be limited to all or part of the same
                  property and assets that secured or, under the written
                  agreements pursuant to which the original Lien arose, could
                  secure the original Lien (plus improvements and accessions to,
                  such property or proceeds or distributions thereof); and

            (B)   the Indebtedness secured by such Lien at such time is not
                  increased to any amount greater than the sum of (x) the
                  outstanding principal amount or, if greater, committed amount
                  of the Indebtedness described under clauses (6), (8), (9),
                  (10), (14) or (15) at the time the original Lien became a
                  Permitted Lien and (y) an amount necessary to pay any fees and
                  expenses,

                                       17

<PAGE>

                  including premiums, related to such refinancing, refunding,
                  extension, renewal or replacement;

      (14)  Liens Incurred in connection with Capital Lease Obligations
            permitted under this Indenture; provided that such Liens do not
            extend or cover any property other than the property that is the
            subject of the Capital Lease Obligation;

      (15)  Liens Incurred to secure Indebtedness permitted under the provisions
            described in clause (b)(16) under Section 4.09 hereof; provided that
            such Liens are limited to the assets or Capital Stock so acquired;

      (16)  Liens in favor of the Company or any Restricted Subsidiary;

      (17)  Liens securing assets (including, without limitation, accounts
            receivable and related assets) sold, conveyed or otherwise
            transferred in connection with a Qualified Securitization
            Transaction; and

      (18)  Liens (other than any Lien Incurred in reliance upon clauses (1)
            through (17) of this definition) with respect to obligations of the
            Company or any Restricted Subsidiary that do not exceed U.S.$60.0
            million in the aggregate at any one time outstanding.

Notwithstanding the foregoing, "Permitted Liens" will not include any Lien
described in clauses (6), (9) or (10) above to the extent such Lien applies to
any Additional Assets acquired directly or indirectly from Net Available Cash
pursuant to Section 4.10 hereof. For purposes of this definition, the term
"Indebtedness" shall be deemed to include interest on such Indebtedness.

      "Person" means any individual, corporation, partnership, limited liability
company, joint venture, association, joint-stock company, trust, unincorporated
organization, government or any agency or political subdivision thereof or any
other entity.

      "Preferred Stock," as applied to the Capital Stock of any Person, means
Capital Stock of any class or classes (however designated) which is preferred as
to the payment of dividends or distributions, or as to the distribution of
assets upon any voluntary or involuntary liquidation or dissolution of such
Person, over shares of Capital Stock of any other class of such Person.

      "Principal" of a Note means the principal of the Note plus the premium, if
any, payable on the Note, which is due or overdue or is to become due at the
relevant time.

      "Purchase Money Note" means a promissory note evidencing a line of credit,
or evidencing other Indebtedness owed to the Company or any Restricted
Subsidiary in connection with a Qualified Securitization Transaction, which note
shall be repaid from cash available to the maker of such note, other than
amounts required to be established as reserves, amounts paid to investors in
respect of interest, principal and other amounts owing to such investors and
amounts paid in connection with the purchase of new assets (including, without
limitation, the purchase of newly generated accounts receivable).

                                       18

<PAGE>

      "Put Offer Event" means (i) any proposed liquidation preference payment to
be made with respect to New Preferred Shares by the Company pursuant to Section
4.07(b)(6)(B) herein and (ii) any transaction in which the Company elects to
satisfy the conditions set forth clause (i) of Section 5.01(a).

      "Qualified Securitization Transaction" means any transaction or series of
transactions that may be entered into by the Company or any Restricted
Subsidiary pursuant to which the Company or any Restricted Subsidiary may sell,
convey or otherwise transfer to (a) a Qualified Subsidiary (in the case of a
transfer by the Company or any Restricted Subsidiary) and (b) any other person
(in the case of a transfer by a Qualified Subsidiary), or may grant a security
interest in, any asset (whether now existing or arising in the future) of the
Company or any Restricted Subsidiary, including without limitation, accounts
receivable (whether now existing or arising in the future) of the Company or any
Restricted Subsidiary and any asset related thereto, including, without
limitation, all collateral securing the accounts receivable, all contracts and
all guarantees or rights and other obligations in respect of the accounts
receivable, proceeds of the accounts receivable and other assets which are
customarily transferred, or in respect of which security interests are
customarily granted, in connection with asset securitization transactions
involving such asset or assets. For purposes of clarification, a Qualified
Securitization Transaction includes, without limitation, any transaction or
series of transactions intended to qualify with the "true sale" requirements of
applicable Mexican law.

      "Qualified Subsidiary" means a Subsidiary of the Company (or a security
administration trust organized under Mexican law of which the Company or a
Restricted Subsidiary is a beneficiary) which engages in no activities other
than in connection with Qualified Securitization Transaction and related
activities, including, without limitation, the purchase or financing of accounts
receivables, and which is designated by the Board of Directors of the Company
(as provided below) as a Qualified Subsidiary with which neither the Company nor
any other Restricted Subsidiary has any material contract, agreement,
arrangement or understanding (except in connection with a Purchase Money Note or
Qualified Securitization Transaction and other agreements ancillary thereto)
other than on terms no less favorable to the Company or such other Restricted
Subsidiary than those that might be obtained at the time from persons that are
not Affiliates of the Company, other than fees payable in the ordinary course of
business in connection with servicing assets, including billing, collecting,
monitoring and other servicing of accounts receivable. Any designation of a
Subsidiary of the Company as a Qualified Subsidiary shall be evidenced to the
Trustee by filing with the Trustee a certified copy of the Board Resolution of
the Board of Directors of the Company giving effect to such designation and an
Officers Certificate certifying that the designation complied with the preceding
conditions and was permitted by the Indenture.

      "Recapitalization" means the transactions with respect to changes to the
capital structure of the Company and governance rights of the holders of Capital
Stock of the Company as set forth in the Offering Circular, including the
issuance of the New Preferred Shares and the designation and election or
appointment of directors to the Board of Directors.

      "Refinance" means, in respect of any Indebtedness, to refinance, extend,
renew, refund, repay, prepay, redeem, defease or retire, or to issue other
Indebtedness in exchange or

                                       19

<PAGE>

replacement for, such indebtedness. "Refinanced" and "Refinancing" shall have
correlative meanings.

      "Refinancing Indebtedness" means Indebtedness that Refinances any
Indebtedness of the Company or any Restricted Subsidiary existing on the Issue
Date or Incurred in compliance with this Indenture, including Indebtedness that
Refinances Refinancing Indebtedness; provided, however, that:

      (1)   such Refinancing Indebtedness has a Stated Maturity no earlier than
            the Stated Maturity of the Indebtedness being Refinanced;

      (2)   such Refinancing Indebtedness has an Average Life at the time such
            Refinancing Indebtedness is Incurred that is equal to or greater
            than the Average Life of the Indebtedness being Refinanced; and

      (3)   such Refinancing Indebtedness has an aggregate principal amount (or
            if Incurred with original issue discount, an aggregate issue price)
            that is equal to or less than the aggregate principal amount (or if
            Incurred with original issue discount, the aggregate accreted value)
            then outstanding or committed (plus fees and expenses, including any
            premium and defeasance costs) under the Indebtedness being
            Refinanced;

provided further, however, that Refinancing Indebtedness shall not include (A)
Indebtedness of a Subsidiary that Refinances Indebtedness of the Company or (B)
Indebtedness of the Company or a Restricted Subsidiary that Refinances
Indebtedness of an Unrestricted Subsidiary.

      "Related Business" means any business in which the Company was engaged on
the Issue Date and any other business related, ancillary or complementary to any
business of the Company in which the Company was engaged on the Issue Date.

      "Responsible Officer" means, when used with respect to the Trustee, any
officer within the corporate trust department of the Trustee, including any vice
president, assistant vice president, assistant secretary, assistant treasurer,
trust officer or any other officer of the Trustee who customarily performs
functions similar to those performed by the persons who at the time shall be
such officers, respectively, or to whom any corporate trust matter is referred
because of such person's knowledge of and familiarity with the particular
subject and who shall have direct responsibility for the administration of this
Indenture.

      "Restricted Payment" with respect to any Person means:

      (1)   the declaration or payment of any dividends or any other
            distributions of any sort in respect of its Capital Stock (including
            any payment in connection with any merger or consolidation involving
            such Person) or similar payment to the direct or indirect holders of
            its Capital Stock (other than dividends or distributions payable
            solely in its Capital Stock (other than Disqualified Stock) and
            dividends or distributions payable solely to the Company or a
            Restricted Subsidiary, and other than pro rata dividends or other
            distributions made by a Subsidiary that is not a

                                       20
<PAGE>

            Wholly Owned Subsidiary to minority stockholders (or owners of an
            equivalent interest in the case of a Subsidiary that is an entity
            other than a corporation));

      (2)   the purchase, redemption or other acquisition or retirement for
            value of any Capital Stock of the Company held by any Person or of
            any Capital Stock of a Restricted Subsidiary held by any Affiliate
            of the Company (other than a Restricted Subsidiary), including the
            exercise of any option to exchange any Capital Stock (other than
            into Capital Stock of the Company that is not Disqualified Stock),
            other than the purchase, redemption or other acquisition or
            retirement for value of any New Preferred Shares (i) if the Company
            makes a Put Offer pursuant to Section 4.15 within 60 days prior to
            the purchase, redemption or other acquisition or retirement for
            value of such New Preferred Shares or (ii) for Capital Stock in any
            Person (or any Affiliate thereof) that (A) acquires or holds a
            majority of the Capital Stock of the Company (whether by merger,
            consolidation, share purchase or otherwise) or (B) acquires all or
            substantially all of the assets of the Company in a transaction in
            which the Company elects to satisfy the conditions set forth in
            clause (ii) of Section 5.01(a);

      (3)   the payment of principal or interest in cash prior to the scheduled
            maturity or interest payment date of any Subordinated Obligations of
            such Person or the purchase, repurchase, redemption, defeasance or
            other acquisition or retirement for value, prior to scheduled
            maturity, scheduled repayment or scheduled sinking fund payment of
            any Subordinated Obligations of such Person (other than the
            purchase, repurchase or other acquisition of Subordinated
            Obligations purchased in anticipation of satisfying a sinking fund
            obligation, principal installment or final maturity, in each case
            due within one year of the date of such purchase, repurchase or
            other acquisition); or

      (4)   the making of any Investment (other than a Permitted Investment) in
            any Person.

      "Restricted Subsidiary" means any Subsidiary of the Company that is not
(i) an Unrestricted Subsidiary or (ii) a Qualified Subsidiary.

      "Sale/Leaseback Transaction" means an arrangement relating to property
owned by the Company or a Restricted Subsidiary on the Issue Date or thereafter
acquired by the Company or a Restricted Subsidiary whereby the Company or a
Restricted Subsidiary transfers such property to a Person and the Company or a
Restricted Subsidiary leases it from such Person.

      "Securities Act" means the Securities Act of 1933, as amended.

      "SEC" means the Securities and Exchange Commission.

      "Senior Indebtedness" means:

      (1)   Indebtedness of the Company, whether outstanding on the Issue Date
            or thereafter Incurred; and

                                       21
<PAGE>

      (2)   accrued and unpaid interest (including interest accruing on or after
            the filing of any petition in bankruptcy or for reorganization
            relating to the Company to the extent post-filing interest is
            allowed in such proceeding) in respect of (A) indebtedness of the
            Company for money borrowed and (B) indebtedness evidenced by notes,
            debentures, bonds or other similar instruments for the payment of
            which the Company is responsible or liable

unless, in the case of clauses (1) and (2), in the instrument creating or
evidencing the same or pursuant to which the same is outstanding, it is provided
that such obligations are subordinate in right of payment to the Notes;
provided, however, that Senior Indebtedness shall not include:

      (3)   any obligation of the Company to any Subsidiary;

      (4)   any liability for Federal, state, local or other taxes owed or owing
            by the Company;

      (5)   any accounts payable or other liability to trade creditors arising
            in the ordinary course of business (including guarantees thereof or
            instruments evidencing such liabilities);

      (6)   any Indebtedness of the Company (and any accrued and unpaid interest
            in respect thereof) which is subordinate or junior in any respect to
            any other Indebtedness or other obligation of the Company; or

      (7)   that portion of any Indebtedness which at the time of Incurrence is
            Incurred in violation of this Indenture.

      "Significant Subsidiary" means any Restricted Subsidiary that would be a
"Significant Subsidiary" of the Company within the meaning of Rule 1-02 under
Regulation S-X promulgated by the SEC.

      "Stated Maturity" means, with respect to any security, the date specified
in such security as the fixed date on which the final payment of principal of
such security is due and payable, including pursuant to any mandatory redemption
provision (but excluding any provision providing for the repurchase of such
security at the option of the holder thereof upon the happening of any
contingency unless such contingency has occurred).

      "Subordinated Obligation" means any Indebtedness of the Company or a
Guarantor (whether outstanding on the Issue Date or thereafter Incurred) which
is subordinate or junior in right of payment to the Notes or Subsidiary
Guarantee, as applicable, pursuant to a written agreement to that effect.

      "Subsidiary" means, with respect to any Person, any corporation,
association, partnership or other business entity of which more than 50% of the
total voting power of shares of Voting Stock is at the time owned or controlled,
directly or indirectly, by:

      (1)   such Person;

                                       22
<PAGE>

      (2)   such Person and one or more Subsidiaries of such Person; or

      (3)   one or more Subsidiaries of such Person.

      "Subsidiary Guarantee" means the Guarantee by each Guarantor of the
Company's payment obligations under this Indenture and on the Notes, executed
pursuant to the provisions of this Indenture.

      "Telecommunications Business" means the business of (1) transmitting or
providing services relating to the transmission of voice, video or data through
owned or leased terrestrial transmission facilities, (2) constructing,
installing, maintaining, creating, developing or marketing
communications-related network infrastructure, components, equipment, software
and other devices for use in a telecommunications business and related or
incidental thereto, (3) billing, monitoring, collecting and other servicing of
assets related to any business identified in clause (1) or (2) above, including,
without limitation, billing, collecting and other servicing of accounts
receivable and (4) any other business reasonably related, ancillary or
complimentary to those identified in clause (1), (2) or (3) above.

      "Temporary Cash Investments" means any of the following:

      (1)   any investment in direct obligations of the United States of America
            or any agency thereof or obligations guaranteed by the United States
            of America or any agency thereof;

      (2)   investments in time deposit accounts, certificates of deposit and
            money market deposits maturing within 180 days of the date of
            acquisition thereof issued by a bank or trust company which is
            organized under the laws of the United States of America, any state
            thereof or any foreign country recognized by the United States, and
            which bank or trust company has capital, surplus and undivided
            profits aggregating in excess of U.S.$50,000,000 (or the foreign
            currency equivalent thereof) and has outstanding debt which is rated
            "A" (or such similar equivalent rating) or higher by at least one
            nationally recognized statistical rating organization (as defined in
            Rule 436 under the Securities Act) or any money-market fund
            sponsored by a registered broker dealer or mutual fund distributor;

      (3)   repurchase obligations with a term of not more than 30 days for
            underlying securities of the types described in clause (1) above
            entered into with a bank meeting the qualifications described in
            clause (2) above;

      (4)   investments in commercial paper, maturing not more than 90 days
            after the date of acquisition, issued by a corporation (other than
            an Affiliate of the Company) organized and in existence under the
            laws of the United States of America or any foreign country
            recognized by the United States of America with a rating at the time
            as of which any investment therein is made of "P-1" (or higher)
            according to Moody's Investors Service, Inc. or "A-l" (or higher)
            according to Standard and Poor's Ratings Group;

                                       23
<PAGE>

      (5)   investments in securities with maturities of six months or less from
            the date of acquisition issued or fully guaranteed by any state,
            commonwealth or territory of the United States of America, or by any
            political subdivision or taxing authority thereof, and rated at
            least "A" by Standard & Poor's Ratings Group or "A" by Moody's
            Investors Service, Inc.;

      (6)   Certificados de la Tesoreria de la Federacion (Cetes) or Bonos de
            Desarrollo del Gobierno Federal (Bondes) issued by the Mexican
            government and maturing not more than 180 days after the acquisition
            thereof; and

      (7)   certificates of deposit, bank promissory notes and bankers'
            acceptances denominated in Pesos, maturing not more than 180 days
            after the acquisition thereof and issued or Guaranteed by any one of
            the five largest banks (based on assets as of the immediately
            preceding December 31) organized under the laws of Mexico and which
            are not under intervention or controlled by the Instituto para la
            Proteccion al Ahorro Bancario, or any successor thereto.

      "TIA" means the Trust Indenture Act of 1939 (15 U.S.C. Sections
77aaa-77bbbb) as in effect on the date on which this Indenture is qualified
under the TIA.

      "Trustee" means the party named as such above until a successor replaces
it in accordance with the applicable provisions of this Indenture and thereafter
means the successor serving hereunder.

      "Unrestricted Subsidiary" means:

      (1)   any Subsidiary of the Company that at the time of determination
            shall be designated an Unrestricted Subsidiary by the Board of
            Directors in the manner provided below; and

      (2)   any Subsidiary of an Unrestricted Subsidiary.

The Board of Directors may designate any Subsidiary of the Company (including
any newly acquired or newly formed Subsidiary) to be an Unrestricted Subsidiary
unless such Subsidiary or any of its Subsidiaries owns any Capital Stock or
Indebtedness of, or holds any Lien on any property of, the Company or any other
Subsidiary of the Company that is not a Subsidiary of the Subsidiary to be so
designated; provided, however, that either (A) the Subsidiary to be so
designated has total assets of U.S.$1.00 or less or (B) if such Subsidiary has
assets greater than U.S.$1.00, such designation would be permitted under Section
4.07 hereof.

      The Board of Directors may designate any Unrestricted Subsidiary to be a
Restricted Subsidiary; provided, however, that immediately after giving effect
to such designation (A) the Company could Incur U.S.$1.00 of additional
Indebtedness under paragraph (a) of Section 4.09 hereof and (B) no Default shall
have occurred and be continuing. Any such designation by the Board of Directors
shall be evidenced to the Trustee by promptly filing with the Trustee a copy of
the resolution of the Board of Directors giving effect to such designation and
an Officers' Certificate certifying that such designation complied with the
foregoing provisions.

                                       24
<PAGE>

      "U.S. Government Obligations" means direct obligations (or certificates
representing an ownership interest in such obligations) of the United States of
America (including any agency or instrumentality thereof) for the payment of
which the full faith and credit of the United States of America is pledged and
which are not callable at the issuer's option.

      "Voting Stock" of a Person means all classes of Capital Stock or other
interests (including partnership interests) of such Person then outstanding and
normally entitled (without regard to the occurrence of any contingency) to vote
in the election of directors, managers or trustees thereof, including without
limitation, shares of capital stock with limited voting rights (acciones con
caracter de inversion neutra) such as the Company's Series N2 Shares deposited
in one or more trusts which will issue ordinary participation certificates or
CPOs.

      "Warrant Agreement" means that certain warrant agreement, dated March 17,
2000, between the Company and The Bank of New York, as warrant agent thereunder.

      "Warrant Shares" means shares of Capital Stock of the Company issued or
issuable upon the exercise of the Warrants.

      "Warrants" means any of the warrants issued by the Company pursuant to the
Warrant Agreement.

      "Wholly Owned Subsidiary" means a Restricted Subsidiary all the Capital
Stock of which (other than directors' qualifying shares) is owned by the Company
or one or more Wholly Owned Subsidiaries.

SECTION 1.02    Other Definitions.

<TABLE>
<CAPTION>
                                                                                    Defined in
Term                                                                                 Section
----                                                                                ----------
<S>                                                                                 <C>
"Additional Amounts"............................................................       4.19
"Affiliate Transaction".........................................................       4.11
"Asset Sale Offer"..............................................................       3.09
"Authentication Order"..........................................................       2.02
"Covenant Defeasance"...........................................................       8.03
"DTC"...........................................................................       2.03
"Event of Default"..............................................................       6.01
"Excess Proceeds"...............................................................       4.10
"Excessive Additional Amounts"..................................................       3.07
"Exchange Offer"................................................................     Preamble
"Exit Transaction"..............................................................     5.01(a)
"Excluded Taxes"................................................................       4.20
"Legal Defeasance"..............................................................       8.02
"Offer Period"..................................................................       3.09
"Original Indenture"............................................................     Preamble
"Paying Agent"..................................................................       2.03
</TABLE>

                                       25
<PAGE>

<TABLE>
<CAPTION>
                                                                                    Defined in
Term                                                                                 Section
----                                                                                ----------
<S>                                                                                 <C>
"Permitted Debt"................................................................       4.09
"Purchase Date".................................................................       3.09
"Put Offer".....................................................................       4.15
"Put Offer Period"..............................................................       4.15
"Put Payment"...................................................................       4.15
"Put Payment Date"..............................................................       4.15
"Put Purchase Price"............................................................       4.15
"Registrar".....................................................................       2.03
"Successor Company".............................................................       5.01
"Successor Jurisdiction"........................................................       4.19
"Taxes".........................................................................       4.19
</TABLE>

SECTION 1.03    Incorporation by Reference of Trust Indenture Act.

      Whenever this Indenture refers to a provision of the TIA, the provision is
incorporated by reference in and made a part of this Indenture.

      The following TIA terms used in this Indenture have the following
meanings:

      "indenture securities" means the Notes;

      "indenture security Holder" means a Holder of a Note;

      "indenture to be qualified" means this Indenture;

      "indenture trustee" or "institutional trustee" means the Trustee; and

      "obligor" on the Notes and the Subsidiary Guarantees means the Company and
the Guarantors, respectively, and any successor obligor upon the Notes and the
Subsidiary Guarantees, respectively.

      All other terms used in this Indenture that are defined by the TIA,
defined by TIA reference to another statute or defined by SEC rule under the TIA
have the meanings so assigned to them.

SECTION 1.04    Rules of Construction.

      Unless the context otherwise requires:

      (a) a term has the meaning assigned to it;

      (b) an accounting term not otherwise defined has the meaning assigned to
it in accordance with GAAP;

      (c) "or" is not exclusive;

                                       26
<PAGE>

      (d) "including" means including, without limitation;

      (e) words in the singular include the plural, and words in the plural
include the singular;

      (f) provisions apply to successive events and transactions; and

      (g) references to sections of or rules under the Securities Act shall be
deemed to include substitute, replacement of successor sections or rules adopted
by the SEC from time to time.

                                    ARTICLE 2

                                    THE NOTES

SECTION 2.01    Form and Dating.

      (a) General. The Notes and the Trustee's certificate of authentication
shall be substantially in the form of Exhibit A hereto. The Notes may have
notations, legends or endorsements required by law, stock exchange rule or
usage. Each Note shall be dated the date of its authentication. The Notes shall
be in denominations of U.S.$1.00 and integral multiples thereof.

      The terms and provisions contained in the Notes shall constitute, and are
hereby expressly made, a part of this Indenture and the Company, each Guarantor
and the Trustee, by their execution and delivery of this Indenture, expressly
agree to such terms and provisions and to be bound thereby. However, to the
extent any provision of any Note conflicts with the express provisions of this
Indenture, the provisions of this Indenture shall govern and be controlling.

      (b) Global Note. Notes issued in global form shall be substantially in the
form of Exhibit A attached hereto (including the Global Note Legend thereon and
the "Schedule of Exchanges of Interests in the Global Note" attached thereto).
Notes issued in definitive form shall be substantially in the form of Exhibit A
attached hereto (but without the Global Note Legend thereon and without the
"Schedule of Exchanges of Interests in the Global Note" attached thereto). The
Global Note shall represent such of the outstanding Notes as shall be specified
therein and each shall provide that it shall represent the aggregate principal
amount of outstanding Notes from time to time endorsed thereon and that the
aggregate principal amount of outstanding Notes represented thereby may from
time to time be reduced or increased, as appropriate, to reflect exchanges and
redemptions. Any endorsement of the Global Note to reflect the amount of any
increase or decrease in the aggregate principal amount of outstanding Notes
represented thereby shall be made by the Trustee or the Custodian, at the
direction of the Trustee, in accordance with instructions given by the Holder
thereof as required by Section 2.06 hereof.

SECTION 2.02    Execution and Authentication.

      One Officer shall sign the Notes for the Company by manual or facsimile
signature.

      If the Officer whose signature is on a Note no longer holds that office at
the time a Note is authenticated, the Note shall nevertheless be valid.

                                       27
<PAGE>

      Each Note shall be dated the date of its authentication.

      A Note shall not be valid until authenticated by the manual signature of
the Trustee. The signature shall be conclusive evidence that the Note has been
authenticated under this Indenture.

      The Trustee shall, upon a written order of the Company signed by one
Officer (an "Authentication Order"), authenticate Notes for original issue up to
the aggregate principal amount stated in paragraph 4 of the Notes. The aggregate
principal amount of Notes outstanding at any time may not exceed such amount
except as provided in Section 2.07 hereof.

      The Trustee may appoint an authenticating agent acceptable to the Company
to authenticate Notes. An authenticating agent may authenticate Notes whenever
the Trustee may do so. Each reference in this Indenture to authentication by the
Trustee includes authentication by such agent. An authenticating agent has the
same rights as an Agent to deal with Holders or an Affiliate of the Company.

SECTION 2.03    Registrar and Paying Agent.

      The Company shall maintain an office or agency where Notes may be
presented for registration of transfer or for exchange ("Registrar") and an
office or agency where Notes may be presented for payment ("Paying Agent"). The
Registrar shall keep a register of the Notes and of their transfer and exchange.
The Company may appoint one or more co-registrars and one or more additional
paying agents. The term "Registrar" includes any co-registrar and the term
"Paying Agent" includes any additional paying agent. The Company may change any
Paying Agent or Registrar without notice to any Holder. The Company shall notify
the Trustee in writing of the name and address of any Agent not a party to this
Indenture. If the Company fails to appoint or maintain another entity as
Registrar or Paying Agent, the Trustee shall act as such. The Company or any of
its Subsidiaries may act as Paying Agent or Registrar.

      The Company initially appoints The Depository Trust Company ("DTC") to act
as Depositary with respect to the Global Note.

      The Company initially appoints the Trustee at its Corporate Trust Office
to act as the Registrar and Paying Agent and to act as Custodian with respect to
the Global Note.

SECTION 2.04    Paying Agent to Hold Money in Trust.

      The Company shall require each Paying Agent other than the Trustee to
agree in writing that the Paying Agent will hold in trust for the benefit of
Holders or the Trustee all money held by the Paying Agent for the payment of
principal, premium, if any, or interest on the Notes, and will notify the
Trustee of any default by the Company in making any such payment. While any such
default continues, the Trustee may require a Paying Agent to pay all money held
by it to the Trustee. The Company at any time may require a Paying Agent to pay
all money held by it to the Trustee. Upon payment over to the Trustee, the
Paying Agent (if other than the Company or a Subsidiary) shall have no further
liability for the money. If the Company or a Subsidiary acts as Paying Agent, it
shall segregate and hold in a separate trust fund for the benefit of the Holders
all money held by it as Paying Agent. Upon any bankruptcy or reorganization
proceedings relating to the Company, the Trustee shall serve as Paying Agent for
the Notes.

                                       28
<PAGE>

SECTION 2.05    Holder Lists.

      The Trustee shall preserve in as current a form as is reasonably
practicable the most recent list available to it of the names and addresses of
all Holders and shall otherwise comply with TIA Section 312(a). If the Trustee
is not the Registrar, the Company shall furnish, or cause the Registrar to
furnish, to the Trustee at least seven Business Days before each interest
payment date and at such other times as the Trustee may request in writing, a
list in such form and as of such date as the Trustee may reasonably require of
the names and addresses of the Holders of Notes and the Company shall otherwise
comply with TIA Section 312(a).

SECTION 2.06    Transfer and Exchange.

      (a) Transfer and Exchange of Global Note. The Global Note may not be
transferred as a whole except by the Depositary to a nominee of the Depositary,
by a nominee of the Depositary to the Depositary or to another nominee of the
Depositary, or by the Depositary or any such nominee to a successor Depositary
or a nominee of such successor Depositary. The Global Note will be exchanged by
the Company for Definitive Notes if (i) the Company delivers to the Trustee
notice from the Depositary that it is unwilling or unable to continue to act as
Depositary or that it is no longer a clearing agency registered under the
Exchange Act and, in either case, a successor Depositary is not appointed by the
Company within 120 days after the date of such notice from the Depositary or
(ii) the Company in its sole discretion determines that the Global Note (in
whole but not in part) should be exchanged for Definitive Notes and delivers a
written notice to such effect to the Trustee. Upon the occurrence of either of
the preceding events in (i) or (ii) above, Definitive Notes shall be issued in
such names as the Depositary shall instruct the Trustee. The Global Note also
may be exchanged or replaced, in whole or in part, as provided in Sections 2.07
and 2.10 hereof. Every Note authenticated and delivered in exchange for, or in
lieu of, the Global Note or any portion thereof, pursuant to this Section 2.06
or Section 2.07 or 2.10 hereof, shall be authenticated and delivered in the form
of, and shall be, the Global Note. The Global Note may not be exchanged for
another Note other than as provided in this Section 2.06(a); however, beneficial
interests in the Global Note may be transferred and exchanged as provided in
Section 2.06(b) or (c) hereof.

      (b) Transfer and Exchange of Beneficial Interests in the Global Note. The
transfer and exchange of beneficial interests in the Global Note shall be
effected through the Depositary, in accordance with the provisions of this
Indenture and the Applicable Procedures. Transfers of beneficial interests in
the Global Note also shall require compliance with either subparagraph (i) or
(ii) below, as applicable, as well as one or more of the other following
subparagraphs, as applicable:

            (i) Transfer of Beneficial Interests in the Global Note. Beneficial
      interests in the Global Note may be transferred to Persons who take
      delivery thereof in the form of a beneficial interest in the Global Note.
      No written orders or instructions shall be required to be delivered to the
      Registrar to effect the transfers described in this Section 2.06(b)(i).

            (ii) All Other Transfers and Exchanges of Beneficial Interests in
      the Global Note. In connection with all transfers and exchanges of
      beneficial interests that are not subject to Section 2.06(b)(i) above, the
      transferor of such beneficial interest must deliver

                                       29
<PAGE>

      to the Registrar (1) a written order from a Participant or an Indirect
      Participant given to the Depositary in accordance with the Applicable
      Procedures directing the Depositary to cause to be issued a Definitive
      Note in an amount equal to the beneficial interest to be transferred or
      exchanged and (2) instructions given by the Depositary to the Registrar
      containing information regarding the Person in whose name such Definitive
      Note shall be registered to effect the transfer or exchange referred to in
      (1) above. Upon satisfaction of all of the requirements for transfer or
      exchange of beneficial interests in the Global Note contained in this
      Indenture and the Notes or otherwise applicable under the Securities Act,
      the Trustee shall adjust the principal amount of the Global Note pursuant
      to Section 2.06(g) hereof.

      (c) Transfer or Exchange of Beneficial Interests in the Global Note for
Definitive Notes.

      If any holder of a beneficial interest in the Global Note proposes to
exchange such beneficial interest for a Definitive Note or to transfer such
beneficial interest to a Person who takes delivery thereof in the form of a
Definitive Note, then, upon satisfaction of the conditions set forth in Section
2.06(b)(ii) hereof, the Trustee shall cause the aggregate principal amount of
the Global Note to be reduced accordingly pursuant to Section 2.06(g) hereof,
and the Company shall execute and the Trustee shall authenticate and deliver to
the Person designated in the instructions a Definitive Note in the appropriate
principal amount. Any Definitive Note issued in exchange for a beneficial
interest pursuant to this Section 2.06(c) shall be registered in such name or
names and in such authorized denomination or denominations as the holder of such
beneficial interest shall instruct the Registrar through instructions from the
Depositary and the Participant or Indirect Participant. The Trustee shall
deliver such Definitive Notes to the Persons in whose names such Notes are so
registered.

      (d) Transfer and Exchange of Definitive Notes for Beneficial Interests in
the Global Note.

      A Holder of a Definitive Note may exchange such Note for a beneficial
interest in the Global Note or transfer such Definitive Note to a Person who
takes delivery thereof in the form of a beneficial interest in the Global Note
at any time. Upon receipt of a request for such an exchange or transfer, the
Trustee shall cancel the applicable Definitive Note and increase or cause to be
increased the aggregate principal amount of the Global Note.

      (e) Transfer and Exchange of Definitive Notes for Definitive Notes. Upon
request by a Holder of Definitive Notes and such Holder's compliance with the
provisions of this Section 2.06(e), the Registrar shall register the transfer or
exchange of Definitive Notes. Prior to such registration of transfer or
exchange, the requesting Holder shall present or surrender to the Registrar the
Definitive Notes duly endorsed or accompanied by a written instruction of
transfer in form satisfactory to the Registrar duly executed by such Holder or
by its attorney, duly authorized in writing. In addition, the requesting Holder
shall provide any additional certifications, documents and information, as
applicable, required pursuant to the following provisions of this Section
2.06(e). Upon receipt of a request to register such a transfer, the Registrar
shall register the Definitive Notes pursuant to the instructions from the Holder
thereof.

                                       30
<PAGE>

      (f) Legends. The following legends shall appear on the face of the Global
Note and Definitive Notes issued under this Indenture unless specifically stated
otherwise in the applicable provisions of this Indenture.

            (i) Global Note Legend. The Global Note shall bear a legend in
      substantially the following form:

"THIS GLOBAL NOTE IS HELD BY THE DEPOSITARY (AS DEFINED IN THE INDENTURE
GOVERNING THIS NOTE) OR ITS NOMINEE IN CUSTODY FOR THE BENEFIT OF THE BENEFICIAL
OWNERS HEREOF, AND IS NOT TRANSFERABLE TO ANY PERSON UNDER ANY CIRCUMSTANCES
EXCEPT THAT (I) THE TRUSTEE MAY MAKE SUCH NOTATIONS HEREON AS MAY BE REQUIRED
PURSUANT TO SECTION 2.07 OF THE INDENTURE, (II) THIS GLOBAL NOTE MAY BE
EXCHANGED IN WHOLE BUT NOT IN PART PURSUANT TO SECTION 2.06(a) OF THE INDENTURE,
(III) THIS GLOBAL NOTE MAY BE DELIVERED TO THE TRUSTEE FOR CANCELLATION PURSUANT
TO SECTION 2.11 OF THE INDENTURE AND (IV) THIS GLOBAL NOTE MAY BE TRANSFERRED TO
A SUCCESSOR DEPOSITARY WITH THE PRIOR WRITTEN CONSENT OF THE COMPANY."

            (ii) Original Issue Discount Legend. Each Note shall bear a legend
      in substantially the following form:

"THIS SECURITY WAS ISSUED WITH ORIGINAL ISSUE DISCOUNT UNDER SECTION 1273 OF THE
INTERNAL REVENUE CODE. YOU MAY CONTACT THE CHIEF FINANCIAL OFFICER OF MAXCOM
TELECOMUNICACIONES, S.A. DE C.V. AT GUILLERMO GONZALEZ CAMARENA #2000, COL.
CENTRO DE CIUDAD SANTA FE, 01210 MEXICO D.F., TELEPHONE NUMBER:
011-525-5147-1125, WHO WILL PROVIDE YOU WITH ANY REQUIRED INFORMATION REGARDING
THE ORIGINAL ISSUE DISCOUNT."

      (g) Cancellation and/or Adjustment of the Global Note. At such time as all
beneficial interests in the Global Note have been exchanged for Definitive Notes
or the Global Note has been redeemed, repurchased or canceled in whole and not
in part, the Global Note shall be returned to or retained and canceled by the
Trustee in accordance with Section 2.11 hereof. At any time prior to such
cancellation, if any beneficial interest in the Global Note is exchanged for or
transferred to a Person who will take delivery thereof for Definitive Notes, the
principal amount of Notes represented by the Global Note shall be reduced
accordingly and an endorsement shall be made on the Global Note by the Trustee
or by the Depositary at the direction of the Trustee to reflect such reduction.

      (h) General Provisions Relating to Transfers and Exchanges.

            (i) To permit registrations of transfers and exchanges, the Company
      shall execute and the Trustee shall authenticate the Global Note and
      Definitive Notes upon the Company's order.

            (ii) No service charge shall be made to a holder of a beneficial
      interest in the Global Note or to a Holder of a Definitive Note for any
      registration of transfer or

                                       31
<PAGE>

      exchange, but the Company may require payment of a sum sufficient to cover
      any transfer tax or similar governmental charge payable in connection
      therewith (other than any such transfer taxes or similar governmental
      charge payable upon exchange or transfer pursuant to Sections 2.10, 3.06,
      3.09, 4.10, 4.15, 5.01(a)(i) and 9.05 hereof).

            (iii) The Registrar shall not be required to register the transfer
      of or exchange any Note selected for redemption in whole or in part,
      except the unredeemed portion of any Note being redeemed in part.

            (iv) The Global Note and Definitive Notes issued upon any
      registration of transfer or exchange of another Global Note or Definitive
      Notes shall be the valid obligations of the Company, evidencing the same
      debt, and entitled to the same benefits under this Indenture, as the
      Global Note or Definitive Notes surrendered upon such registration of
      transfer or exchange.

            (v) The Company shall not be required (A) to issue, to register the
      transfer of or to exchange any Notes during a period beginning at the
      opening of business 15 days before the day of any selection of Notes for
      redemption under Section 3.02 hereof and ending at the close of business
      on the day of selection, (B) to register the transfer of or to exchange
      any Note so selected for redemption in whole or in part, except the
      unredeemed portion of any Note being redeemed in part or (C) to register
      the transfer of or to exchange a Note between a record date and the next
      succeeding Interest Payment Date.

            (vi) Prior to due presentment for the registration of a transfer of
      any Note, the Trustee, any Agent and the Company may deem and treat the
      Person in whose name any Note is registered as the absolute owner of such
      Note for the purpose of receiving payment of principal of and interest on
      such Notes and for all other purposes, and none of the Trustee, any Agent
      or the Company shall be affected by notice to the contrary.

            (vii) The Trustee shall authenticate the Global Note and Definitive
      Notes in accordance with the provisions of Section 2.02 hereof.

            (viii) All certifications, certificates and Opinions of Counsel
      required to be submitted to the Registrar pursuant to this Section 2.06 to
      effect a registration of transfer or exchange may be submitted by
      facsimile.

            (ix) The Trustee shall have no obligation or duty to monitor,
      determine or inquire as to compliance with any restrictions on transfer
      imposed under this Indenture or under applicable law with respect to any
      transfer of any interest in any Note (including any transfers between or
      among beneficial owners of interests in the Global Note) other than to
      require delivery of such certificates and other documentation or evidence
      as are expressly required by, and to do so if and when expressly required
      by the terms of, this Indenture, and to examine the same to determine
      substantial compliance as to form with the express requirements hereof.

                                       32
<PAGE>

SECTION 2.07    Replacement Notes.

      If any mutilated Note is surrendered to the Trustee or the Company and the
Trustee receives evidence to its satisfaction of the destruction, loss or theft
of any Note, the Company shall issue and the Trustee, upon receipt of an
Authentication Order, shall authenticate a replacement Note if the Trustee's
requirements are met. If required by the Trustee or the Company, an indemnity
bond must be supplied by the Holder that is sufficient in the judgment of the
Trustee and the Company to protect the Company, the Trustee, any Agent and any
authenticating agent from any loss that any of them may suffer if a Note is
replaced. The Company may charge for its expenses in replacing a Note. In the
event any such mutilated, lost, destroyed or wrongfully taken Note has become
due and payable, the Company in its discretion may pay such Note instead of
issuing a new Note in replacement thereof. If after the delivery of such new
Note, a bona fide purchaser of the original Note in lieu of which such new Note
was issued presents for payment such original Note, the Company and the Trustee
shall be entitled to recover such new Note from the person to whom it was
delivered or any transferee thereof, except a bona fide purchaser, and shall be
entitled to recover upon the security or indemnity provided therefor to the
extent of any loss, damage, cost or expense incurred by the Company or the
Trustee in connection therewith.

      Every replacement Note is an additional obligation of the Company and
shall be entitled to all of the benefits of this Indenture equally and
proportionately with all other Notes duly issued hereunder.

SECTION 2.08    Outstanding Notes.

      The Notes outstanding at any time are all the Notes authenticated by the
Trustee except for those canceled by it, those delivered to it for cancellation,
those reductions in the interest in the Global Note effected by the Trustee in
accordance with the provisions hereof, and those described in this Section as
not outstanding. Except as set forth in Section 2.09 hereof, a Note does not
cease to be outstanding because the Company or an Affiliate of the Company holds
the Note.

      If the principal amount of any Note is considered paid under Section 4.01
hereof, it ceases to be outstanding and interest on it ceases to accrue.

      If the Paying Agent (other than the Company, a Subsidiary or an Affiliate
of any thereof) holds, on a redemption date or maturity date, money sufficient
to pay Notes payable on that date, then on and after that date such Notes shall
be deemed to be no longer outstanding and shall cease to accrue interest.

SECTION 2.09    Treasury Notes.

      In determining whether the Holders of the required principal amount of
Notes have concurred in any direction, waiver or consent, Notes owned by the
Company, or by any Person directly or indirectly controlling or controlled by or
under direct or indirect common control with the Company, shall be considered as
though not outstanding, except that for the purposes of determining whether the
Trustee shall be protected in relying on any such direction, waiver or consent,
only Notes that the Trustee knows are so owned shall be so disregarded.

                                       33
<PAGE>

SECTION 2.10    Temporary Notes.

      Until certificates representing Notes are ready for delivery, the Company
may prepare and the Trustee, upon receipt of an Authentication Order, shall
authenticate temporary Notes. Temporary Notes shall be substantially in the form
of certificated Notes but may have variations that the Company considers
appropriate for temporary Notes and as shall be reasonably acceptable to the
Trustee. Without unreasonable delay, the Company shall prepare and the Trustee
shall authenticate definitive Notes in exchange for temporary Notes.

      Holders of temporary Notes shall be entitled to all of the benefits of
this Indenture.

SECTION 2.11    Cancellation.

      The Company at any time may deliver Notes to the Trustee for cancellation.
The Registrar and Paying Agent shall forward to the Trustee any Notes
surrendered to them for registration of transfer, exchange or payment. The
Trustee and no one else shall cancel all Notes surrendered for registration of
transfer, exchange, payment, replacement or cancellation and shall dispose of
such Notes in accordance with its retention and disposal policy (subject to the
record retention requirement of the Exchange Act). The Company may not issue new
Notes to replace Notes that it has paid or that have been delivered to the
Trustee for cancellation. The Trustee shall provide the Company with a list of
all Notes that have been cancelled.

SECTION 2.12    Defaulted Interest.

      If the Company defaults in a payment of interest on the Notes, it shall
pay the defaulted interest in any lawful manner plus, to the extent lawful,
interest payable on the defaulted interest, to the Persons who are Holders on a
subsequent special record date, in each case at the rate provided in the Notes
and in Section 4.01 hereof. The Company shall notify the Trustee in writing of
the amount of defaulted interest proposed to be paid on each Note and the date
of the proposed payment. The Company shall fix or cause to be fixed each such
special record date and payment date, provided that no such special record date
shall be less than 10 days prior to the related payment date for such defaulted
interest. At least 15 days before the special record date, the Company (or, upon
the written request of the Company, the Trustee in the name and at the expense
of the Company) shall mail or cause to be mailed to Holders a notice that states
the special record date, the related payment date and the amount of such
interest to be paid.

                                   ARTICLE 3

                            REDEMPTION AND PREPAYMENT

SECTION 3.01    Notices to Trustee.

      If the Company elects to redeem Notes pursuant to the optional redemption
provisions of Section 3.07 hereof, it shall furnish to the Trustee, at least 45
days but not more than 60 days before a redemption date, an Officers'
Certificate setting forth (i) the clause of this Indenture pursuant to which the
redemption shall occur, (ii) the redemption date, (iii) the principal amount of
Notes to be redeemed and (iv) the redemption price.

                                       34
<PAGE>

SECTION 3.02    Selection of Notes to Be Redeemed.

      If less than all of the Notes are to be redeemed or purchased in an offer
to purchase at any time, the Trustee shall select the Notes to be redeemed or
purchased among the Holders of the Notes in compliance with the requirements of
the principal national securities exchange, if any, on which the Notes are
listed or, if the Notes are not so listed, on a pro rata basis, by lot or in
accordance with any other method the Trustee considers fair and appropriate. In
the event of partial redemption by lot, the particular Notes to be redeemed
shall be selected, unless otherwise provided herein, not less than 45 nor more
than 60 days prior to the redemption date by the Trustee from the outstanding
Notes not previously called for redemption.

      The Trustee shall promptly notify the Company in writing of the Notes
selected for redemption and, in the case of any Note selected for partial
redemption, the principal amount thereof to be redeemed. Notes and portions of
Notes selected shall be in amounts of U.S.$1.00 or whole multiples of U.S.$1.00;
except that if all of the Notes of a Holder are to be redeemed, the entire
outstanding amount of Notes held by such Holder, even if not a multiple of
U.S.$1.00, shall be redeemed. Except as provided in the preceding sentence,
provisions of this Indenture that apply to Notes called for redemption also
apply to portions of Notes called for redemption.

SECTION 3.03    Notice of Redemption.

      Subject to the provisions of Section 3.09 hereof, at least 30 days but not
more than 60 days before a redemption date, the Company shall mail or cause to
be mailed, by first class mail, a notice of redemption to each Holder whose
Notes are to be redeemed at its registered address.

      The notice shall identify the Notes to be redeemed (including the CUSIP
number) and shall state:

      (a) the redemption date;

      (b) the redemption price;

      (c) if any Note is being redeemed in part, the portion of the principal
amount of such Note to be redeemed and that, after the redemption date upon
surrender of such Note, a new Note or Notes in principal amount equal to the
unredeemed portion shall be issued upon cancellation of the original Note;

      (d) the name and address of the Paying Agent;

      (e) that Notes called for redemption must be surrendered to the Paying
Agent to collect the redemption price;

      (f) that, unless the Company defaults in making such redemption payment,
interest and Additional Amounts, if any, on Notes called for redemption ceases
to accrue on and after the redemption date;

      (g) the paragraph of the Notes and/or Section of this Indenture pursuant
to which the Notes called for redemption are being redeemed; and

                                       35
<PAGE>

      (h) that no representation is made as to the correctness or accuracy of
the CUSIP number, if any, listed in such notice or printed on the Notes.

      At the Company's request, the Trustee shall give the notice of redemption
in the Company's name and at its expense; provided, however, that the Company
shall have delivered to the Trustee, at least 45 days prior to the redemption
date, an Officers' Certificate requesting that the Trustee give such notice and
setting forth the information to be stated in such notice as provided in the
preceding paragraph.

SECTION 3.04    Effect of Notice of Redemption.

      Once notice of redemption is mailed in accordance with Section 3.03
hereof, Notes called for redemption become irrevocably due and payable on the
redemption date at the redemption price. A notice of redemption may not be
conditional.

SECTION 3.05    Deposit of Redemption Price.

      One Business Day prior to the redemption date, the Company shall deposit
with the Trustee or with the Paying Agent money sufficient to pay the redemption
price of and accrued and unpaid interest and Additional Amounts, if any, on all
Notes to be redeemed on that date. The Trustee or the Paying Agent shall
promptly return to the Company any money deposited with the Trustee or the
Paying Agent by the Company in excess of the amounts necessary to pay the
redemption price of, and accrued and unpaid interest on, all Notes to be
redeemed.

      If the Company complies with the provisions of the preceding paragraph, on
and after the redemption date, interest and Additional Amounts, if any, shall
cease to accrue on the Notes or the portions of Notes called for redemption. If
a Note is redeemed on or after an interest record date but on or prior to the
related interest payment date, then any accrued and unpaid interest and
Additional Amounts, if any, shall be paid to the Person in whose name such Note
was registered at the close of business on such record date. If any Note called
for redemption shall not be so paid upon surrender for redemption because of the
failure of the Company to comply with the preceding paragraph, interest shall be
paid on the unpaid principal, from the redemption date until such principal is
paid, and to the extent lawful on any interest not paid on such unpaid
principal, in each case at the rate provided in the Notes and in Section 4.01
hereof.

SECTION 3.06    Notes Redeemed in Part.

      Upon surrender of a Note that is redeemed in part, the Company shall issue
and, upon the Company's written request, the Trustee shall authenticate for the
Holder at the expense of the Company a new Note equal in principal amount to the
unredeemed portion of the Note surrendered.

SECTION 3.07    Optional Redemption.

      (a) The Company may at its option on one or more occasions redeem Notes in
whole or in part at a redemption price (expressed as a percentage of principal
amount) of 101.00%, plus accrued and unpaid interest and Additional Amounts, if
any, to the redemption date.

                                       36
<PAGE>

      (b) Without the consent of any Holder, outstanding Notes may be redeemed
at the Company's option at any time in whole, but not in part, upon its giving
irrevocable prior written notice pursuant to Section 3.03 hereof, if, as a
result of any amendment to, or change in, the laws (or any related regulation or
rulings) of Mexico or any related political subdivision or taxing authority
affecting taxation or any amendment to or change in an official interpretation,
administration or application of such laws, regulations or rulings (including a
holding by a court of competent jurisdiction), which amendment or change of such
laws, regulations or rulings becomes effective on or after the date on which the
Notes are originally issued, the Company would or would become obligated, after
taking reasonable measures available to the Company to avoid such requirement,
to pay Additional Amounts (as defined in Section 4.19 hereof) in respect of any
Note pursuant to its terms and conditions in excess of the Additional Amounts
the Company would be obligated to pay if payments made on the Notes were subject
to withholding or deduction of Mexican Taxes at a rate of 4.9 percent
("Excessive Additional Amounts") at a cash price equal to the sum of:

            (i) 100% of the principal amount of the Note on the date of
      redemption;

            (ii) the related accrued and unpaid interest, if any, to the date of
      redemption; and

            (iii) any Additional Amounts which would otherwise be payable.

      Notwithstanding the above, no such notice of redemption may be given
earlier than 60 days prior to the earliest date on which, but for such
redemption, the Company would be obligated to pay Excessive Additional Amounts
were any payment on the Notes then due.

      Prior to the mailing of any notice of redemption pursuant to this Section
3.07(b), the Company will deliver to the Trustee (1) an Officer's Certificate
stating that the Company is entitled to effect such redemption and setting forth
a statement of facts showing that the conditions precedent to its right to so
redeem the Notes have occurred and (2) a written opinion of independent counsel
in Mexico in English reasonably acceptable to the Trustee to the effect that the
Company has or will become obligated to pay such Excessive Additional Amounts as
a result of such change or amendment. Once the Company delivers such notice to
the Trustee, it will be irrevocable.

      (c) Any redemption pursuant to this Section 3.07 shall be made pursuant to
the provisions of Section 3.01 through 3.06 hereof.

SECTION 3.08    Mandatory Redemption; Open Market Purchases.

      The Company shall not be required to make mandatory redemption payments
with respect to the Notes. The Company may at any time and from time to time
purchase Notes in the open market.

                                       37
<PAGE>

SECTION 3.09    Offer to Purchase by Application of Excess Proceeds.

      In the event that, pursuant to Section 4.10 hereof, the Company shall be
required to commence an offer to all Holders to purchase Notes (an "Asset Sale
Offer"), it shall follow the procedures specified below.

      In the event of an Asset Disposition that requires the purchase of the
Notes (and other Senior Indebtedness) pursuant to clause (a)(4) of Section 4.10
hereof, the Company will purchase Notes tendered pursuant to an offer by the
Company for the Notes (and such other Senior Indebtedness) at a purchase price
of 100% of their principal amount (or, in the event such other Senior
Indebtedness was issued with significant original issue discount, 100% of the
accreted value thereof) without premium, plus accrued but unpaid interest (or,
in respect of such other Senior Indebtedness, such lesser price, if any, as may
be provided for by the terms of such Senior Indebtedness) in accordance with the
procedures (including prorating in the event of oversubscription) set forth in
this Indenture. If the aggregate purchase price of Notes (and any other Senior
Indebtedness) tendered pursuant to such offer is less than the Net Available
Cash allotted to the purchase thereof, the Company will be required to apply the
remaining Net Available Cash only for purposes not prohibited in this Indenture.
If the aggregate purchase price of the securities tendered exceeds the Net
Available Cash allotted to their purchase, the Company will select the
securities to be purchased on a pro rata basis but in round denominations, which
in the case of the Notes will be denominations of U.S.$1.00 principal amount or
multiples thereof. The Company shall not be required to make such an offer to
purchase Notes (and other Senior Indebtedness) pursuant to Section 4.10 hereof
if the Net Available Cash available therefor is less than U.S.$5.0 million
(which lesser amount shall be carried forward for purposes of determining
whether such an offer is required with respect to the Net Available Cash from
any subsequent Asset Disposition).

      The Company will comply, to the extent applicable, with the requirements
of Section 14(e) of the Exchange Act and any other securities laws or
regulations in connection with the repurchase of Notes pursuant to Section 4.10
hereof. To the extent that the provisions of any securities laws or regulations
conflict with provisions of Section 4.10 hereof, the Company will comply with
the applicable securities laws and regulations and will not be deemed to have
breached its obligations under this clause by virtue of its compliance with such
securities laws or regulations.

      The Asset Sale Offer shall remain open for a period of 20 Business Days
following its commencement and no longer, except to the extent that a longer
period is required by applicable law (the "Offer Period"). No later than five
Business Days after the termination of the Offer Period (the "Purchase Date"),
the Company shall purchase the principal amount of Notes required to be
purchased hereunder in the manner set forth above. Payment for any Notes so
purchased shall be made in the same manner as interest payments are made.

      If the Purchase Date is on or after an interest record date and on or
before the related interest payment date, any accrued and unpaid interest and
Additional Amounts, if any, shall be paid to the Person in whose name a Note is
registered at the close of business on such record date, and no additional
interest shall be payable to Holders who tender Notes pursuant to the Asset Sale
Offer.

                                       38
<PAGE>

      Upon the commencement of an Asset Sale Offer, the Company shall send, by
first class mail, a notice to the Trustee and each of the Holders. The notice
shall contain all instructions and materials necessary to enable such Holders to
tender Notes pursuant to the Asset Sale Offer. The Asset Sale Offer shall be
made to all Holders. The notice, which shall govern the terms of the Asset Sale
Offer, shall state:

      (a) that the Asset Sale Offer is being made pursuant to this Section 3.09
and Section 4.10 hereof and the length of time the Asset Sale Offer shall remain
open;

      (b) the Offer Amount, the purchase price and the Purchase Date;

      (c) that any Note not tendered or accepted for payment shall continue to
accrete or accrue interest and Additional Amounts, if applicable;

      (d) that, unless the Company defaults in making such payment, any Note
accepted for payment pursuant to the Asset Sale Offer shall cease to accrete or
accrue interest and Additional Amounts, if applicable, after the Purchase Date;

      (e) that Holders electing to have a Note purchased pursuant to an Asset
Sale Offer may elect to have Notes purchased in integral multiples of U.S.$1.00
only;

      (f) that Holders electing to have a Note purchased pursuant to any Asset
Sale Offer shall be required to surrender the Note, with the form entitled
"Option of Holder to Elect Purchase" on the reverse of the Note completed, or
transfer by book-entry transfer, to the Company, a depositary, if appointed by
the Company, or a Paying Agent at the address specified in the notice at least
three days before the Purchase Date;

      (g) that Holders shall be entitled to withdraw their election if the
Company, the depositary or the Paying Agent, as the case may be, receives, not
later than the expiration of the Offer Period, a telegram, telex, facsimile
transmission or letter setting forth the name of the Holder, the principal
amount of the Note the Holder delivered for purchase and a statement that such
Holder is withdrawing his election to have such Note purchased;

      (h) that, if the aggregate principal amount of Notes surrendered by
Holders exceeds the Offer Amount, the Company shall select the Notes to be
purchased on a pro rata basis (with such adjustments as may be deemed
appropriate by the Company so that only Notes in denominations of U.S.$1.00, or
integral multiples thereof, shall be purchased); and

      (i) that Holders whose Notes were purchased only in part shall be issued
new Notes equal in principal amount to the unpurchased portion of the Notes
surrendered (or transferred by book-entry transfer).

      On or before the Purchase Date, the Company shall, to the extent lawful,
accept for payment, on a pro rata basis to the extent necessary, the Offer
Amount of Notes or portions thereof tendered pursuant to the Asset Sale Offer,
or if less than the Offer Amount has been tendered, all Notes tendered, deposit
by 10:00 a.m. New York City time, on such date with the Paying Agent an amount
equal to Asset Sale Offer Amount, plus any accrued and unpaid interest and
Additional Amounts, if any, in respect of all Notes, or portions thereof, so
accepted and shall

                                       39
<PAGE>

deliver to the Trustee an Officers' Certificate stating that such Notes or
portions thereof were accepted for payment by the Company in accordance with the
terms of this Section 3.09. The Company, the Depositary or the Paying Agent, as
the case may be, shall promptly (but in any case not later than five days after
the Purchase Date) mail or deliver to each tendering Holder an amount equal to
the purchase price of the Notes tendered by such Holder and accepted by the
Company for purchase, and the Company shall promptly issue a new Note, and the
Trustee, upon written request from the Company shall authenticate and mail or
deliver such new Note to such Holder, in a principal amount equal to any
unpurchased portion of the Note surrendered. Any Note not so accepted shall be
promptly mailed or delivered by the Company to the Holder thereof. The Company
shall publicly announce the results of the Asset Sale Offer on the Purchase
Date.

      Other than as specifically provided in this Section 3.09, any purchase
pursuant to this Section 3.09 shall be made pursuant to the provisions of
Sections 3.01 through 3.06 hereof.

SECTION 3.10    CUSIP Numbers

      The Company in issuing the Notes may use "CUSIP" numbers (if then
generally in use), and, if so, the Trustee shall use "CUSIP" numbers in notices
of redemption as a convenience to Holders; provided that any such notice may
state that no representation is made as to the correctness of such numbers
either as printed on the Notes or as contained in any notice of a redemption and
that reliance may be placed only on the other identification numbers printed on
the Notes, and any such redemption shall not be affected by any defect in or
omission of such numbers. The Company will promptly notify the Trustee of any
change in the "CUSIP" numbers.

                                    ARTICLE 4

                                    COVENANTS

SECTION 4.01    Payment of Notes.

      The Company shall pay or cause to be paid the principal of, premium, if
any, interest, if any, and Additional Amounts, if any, on the Notes on the dates
and in the manner provided in the Notes. Principal, premium, if any, and
interest shall be considered paid on the date due if the Paying Agent, if other
than the Company or a Subsidiary thereof, holds as of 10:00 a.m. Eastern Time on
the due date money deposited by the Company in immediately available funds and
designated for and sufficient to pay all principal, premium, if any, and
interest, if any, and Additional Amounts, if any, then due.

      The Company shall pay interest (including post-petition interest in any
proceeding under any Bankruptcy Law) on overdue principal at the rate equal to
1.25% per annum in excess of the then applicable interest rate on the Notes to
the extent lawful; it shall pay interest (including post-petition interest in
any proceeding under any Bankruptcy Law) on overdue installments of interest
(without regard to any applicable grace period) at the same rate to the extent
lawful.

                                       40
<PAGE>

SECTION 4.02    Maintenance of Office or Agency.

      The Company shall maintain in the Borough of Manhattan, the City of New
York, an office or agency (which may be an office of the Trustee or an affiliate
of the Trustee, Registrar or co-registrar) where Notes may be surrendered for
registration of transfer or for exchange and where notices and demands to or
upon the Company in respect of the Notes and this Indenture may be served. The
Company shall give prompt written notice to the Trustee of the location, and any
change in the location, of such office or agency. If at any time the Company
shall fail to maintain any such required office or agency or shall fail to
furnish the Trustee with the address thereof, such presentations, surrenders,
notices and demands may be made or served at the Corporate Trust Office of the
Trustee.

      The Company may also from time to time designate one or more other offices
or agencies where the Notes may be presented or surrendered for any or all such
purposes and may from time to time rescind such designations; provided, however,
that no such designation or rescission shall in any manner relieve the Company
of its obligation to maintain an office or agency in the Borough of Manhattan,
the City of New York for such purposes. The Company shall give prompt written
notice to the Trustee of any such designation or rescission and of any change in
the location of any such other office or agency.

      The Company hereby designates the Corporate Trust Office of the Trustee as
one such office or agency of the Company in accordance with Section 2.03.

SECTION 4.03    SEC Reports.

      Whether or not required by the SEC, so long as any Notes are outstanding,
the Company shall furnish to the Holders of the Notes, within the time periods
specified in the SEC's rules and regulations all quarterly and annual financial
information that would be required to be contained in a filing with the SEC on
(1) Form 6-K (provided that the Company shall be deemed to be required to file
(A) such Forms for each of the first three fiscal quarters for each fiscal year
and (B) the information required to be filed with the SEC on Form 8-K, if
applicable, for changes in control, acquisition or disposition of assets,
bankruptcy or receivership and changes in the Company's certifying accountants)
and (2) Form 20-F if the Company were required to file such Forms, including an
"Operating Results and Condition" disclosure section and, with respect to the
annual information only, a report on the annual financial statements by the
Company's certified independent accountants.

      In addition, whether or not required by the SEC, the Company will file a
copy of all of the information and reports referred to in clauses (1) and (2)
above with the SEC for public availability within the time periods specified in
the SEC's rules and regulations (unless the SEC will not accept such a filing)
and make such information available to securities analysts and prospective
investors upon request.

      Delivery of such reports, information and documents to the Trustee is for
informational purposes only and the Trustee's receipt of such shall not
constitute constructive notice of any information contained therein or
determinable from information contained therein, including the

                                       41
<PAGE>

Company's compliance with any of its covenants hereunder (as to which the
Trustee is entitled to rely exclusively on Officers' Certificates).

SECTION 4.04    Compliance Certificate.

      (a) The Company and each Guarantor (to the extent that such Guarantor is
so required under the TIA) shall deliver to the Trustee, within 90 days after
the end of each fiscal year commencing with the end of fiscal year 2004, an
Officers' Certificate signed by two Officers of the Company, one of whom must be
the principal executive officer, principal financial officer, the treasurer or
principal accounting officer stating that a review of the activities of the
Company and its Subsidiaries during the preceding fiscal year has been made
under the supervision of the signing Officers with a view to determining whether
the Company has kept, observed, performed and fulfilled its obligations under
this Indenture, and further stating, as to each such Officer signing such
certificate, that to the best of his or her knowledge the Company has kept,
observed, performed and fulfilled each and every covenant contained in this
Indenture and is not in default in the performance or observance of any of the
terms, provisions and conditions of this Indenture (or, if a Default or Event of
Default shall have occurred, describing all such Defaults or Events of Default
of which he or she may have knowledge and what action the Company is taking or
proposes to take with respect thereto) and that to the best of his or her
knowledge no event has occurred and remains in existence by reason of which
payments on account of the principal of or interest, if any, on the Notes is
prohibited or if such event has occurred, a description of the event and what
action the Company is taking or proposes to take with respect thereto.

      (b) So long as not contrary to the then current recommendations of the
American Institute of Certified Public Accountants or the Mexican Institute of
Public Accountants, the year-end financial statements delivered pursuant to
Section 4.03 above shall be accompanied by a written statement of the Company's
independent public accountants (who shall be a firm of established national
reputation) that in making the examination necessary for certification of such
financial statements, nothing has come to their attention that would lead them
to believe that the Company has violated any provisions of Article 4 or Article
5 hereof or, if any such violation has occurred, specifying the nature and
period of existence thereof, it being understood that such accountants shall not
be liable directly or indirectly to any Person for any failure to obtain
knowledge of any such violation.

      (c) The Company shall, so long as any of the Notes are outstanding,
deliver to the Trustee, forthwith within five Business Days upon any Officer
becoming aware of any Default or Event of Default, an Officers' Certificate
specifying such Default or Event of Default and what action the Company is
taking or proposes to take with respect thereto.

SECTION 4.05    Taxes.

      The Company shall pay, and shall cause each of its Subsidiaries to pay,
prior to delinquency, all material taxes, assessments, and governmental levies
except such as are contested in good faith and by appropriate proceedings or
where the failure to effect such payment is not adverse in any material respect
to the Holders of the Notes.

                                       42
<PAGE>

SECTION 4.06    Stay, Extension and Usury Laws.

      The Company and each of the Guarantors covenants (to the extent that it
may lawfully do so) that it shall not at any time insist upon, plead, or in any
manner whatsoever claim or take the benefit or advantage of, any stay, extension
or usury law wherever enacted, now or at any time hereafter in force, that may
affect the covenants or the performance of this Indenture; and the Company and
each of the Guarantors (to the extent that it may lawfully do so) hereby
expressly waives all benefit or advantage of any such law, and covenants that it
shall not, by resort to any such law, hinder, delay or impede the execution of
any power herein granted to the Trustee, but shall suffer and permit the
execution of every such power as though no such law has been enacted.

SECTION 4.07    Limitation on Restricted Payments.

      (a) The Company shall not, and shall not permit any Restricted Subsidiary,
directly or indirectly, to make a Restricted Payment if at the time the Company
or such Restricted Subsidiary makes such Restricted Payment:

            (1)   a Default shall have occurred and be continuing (or would
                  result therefrom);

            (2)   the Company is not entitled to Incur an additional U.S.$1.00
                  of Indebtedness pursuant to paragraph (a) of Section 4.09
                  hereof; or

            (3)   the aggregate amount of such Restricted Payment and all other
                  Restricted Payments since the Issue Date would exceed the sum
                  of (without duplication):

                  (A)   the remainder of (x) cumulative Consolidated Cash Flow
                        during the period (taken as a single accounting period)
                        beginning on the commencement of the third fiscal
                        quarter of the Company after the Issue Date and ending
                        on the last day of the most recent fiscal quarter ending
                        at least 45 days prior to the date of such Restricted
                        Payment minus (y) the product of 2.75 times cumulative
                        Consolidated Interest Expense during such period; plus

                  (B)   100% of the aggregate Net Cash Proceeds received by the
                        Company from the issuance or sale of its Capital Stock
                        (other than Disqualified Stock) subsequent to the Issue
                        Date (other than an issuance or sale to a Subsidiary of
                        the Company, the issuance of Capital Stock of the
                        Company pursuant to irrevocable commitments made in
                        connection with the Recapitalization prior to the Issue
                        Date, or to the extent such Net Cash Proceeds are
                        utilized as the basis for Incurring Indebtedness
                        pursuant to Section 4.09(b)(15) hereof), including sales
                        to an employee stock ownership plan or to a trust
                        established by the Company or any of its Subsidiaries
                        for the benefit of their employees; provided that the
                        Company receives cash and that the Company does not
                        directly or

                                       43
<PAGE>

                        indirectly finance such purchases of Capital Stock, and
                        100% of any cash contribution subsequent to the Issue
                        Date; plus

                  (C)   the amount by which Indebtedness of the Company is
                        reduced on the Company's balance sheet upon the
                        conversion or exchange (other than by a Subsidiary of
                        the Company) subsequent to the Issue Date of any
                        Indebtedness of the Company convertible or exchangeable
                        for Capital Stock (other than Disqualified Stock) of the
                        Company (less the amount of any cash, or the fair value
                        of any other property, distributed by the Company upon
                        such conversion or exchange); plus

                  (D)   an amount equal to the sum of (x) the net reduction in
                        Investments (other than Permitted Investments) made by
                        the Company or any Restricted Subsidiary in any Person
                        resulting from repurchases, repayments or redemptions of
                        such Investments by such Person, proceeds realized on
                        the sale of such Investments, proceeds representing the
                        return of capital (excluding dividends and distributions
                        to the extent that they are accounted for in
                        Consolidated Cash Flow in clause (3) (A) above) in each
                        case received by the Company or any Restricted
                        Subsidiary, and (y) the portion (proportionate to the
                        Company's equity interest in such Person) of the fair
                        market value of the net assets of such Person at the
                        time such Person is designated a Restricted Subsidiary;
                        provided, however, that the foregoing sum shall not
                        exceed, in the case of any such Person or Persons, the
                        amount of Investments (excluding Permitted Investments)
                        previously made (and treated as a Restricted Payment
                        under this clause (a) (3)) by the Company or any
                        Restricted Subsidiary in such Person.

      (b) The preceding provisions will not prohibit:

            (1)   any Restricted Payment (other than a Restricted Payment
                  described in clause (1) of the definition of "Restricted
                  Payment") made out of the Net Cash Proceeds of the
                  substantially concurrent sale of, or made by exchange for,
                  Capital Stock of the Company (other than Disqualified Stock
                  and other than Capital Stock issued or sold to a Subsidiary of
                  the Company) or a substantially concurrent capital
                  contribution; provided, however, that (A) such Restricted
                  Payment shall be excluded in the calculation of the amount of
                  Restricted Payments and (B) the Net Cash Proceeds from such
                  sale or such capital contribution (to the extent so used for
                  such Restricted Payment) shall be excluded from the
                  calculation of amounts under clause (3) (B) of paragraph (a)
                  above;

            (2)   any purchase, repurchase, redemption, defeasance or other
                  acquisition or retirement for value of Subordinated
                  Obligations made by exchange for, or out of the proceeds of
                  the substantially concurrent sale of, Indebtedness

                                       44
<PAGE>

                  which is permitted to be Incurred pursuant to Section 4.09
                  hereof; provided, however, that such purchase, repurchase,
                  redemption, defeasance or other acquisition or retirement for
                  value shall be excluded in the calculation of the amount of
                  Restricted Payments under clause (a) (3) above;

            (3)   dividends paid within 60 days after the date of declaration
                  thereof if at such date of declaration such dividend would
                  have complied with this Section 4.07; provided, however, that
                  such dividend shall be included in the calculation of the
                  amount of Restricted Payments under clause (a) (3) above
                  (unless already incurred in determining the amount of
                  Restricted Payments previously made upon declaration of such
                  dividend);

            (4)   the repurchase or other acquisition of shares of Capital Stock
                  of the Company or any of its Subsidiaries from employees,
                  former employees, directors or former directors of the Company
                  or any of its Subsidiaries (or permitted transferees of such
                  employees, former employees, directors or former directors),
                  pursuant to the terms of the agreements (including employment
                  agreements) or plans (or amendments thereto) approved by the
                  Board of Directors under which such individuals purchase or
                  sell or are granted the option to purchase or sell, shares of
                  such Capital Stock; provided, however, that the aggregate
                  amount of such repurchases and other acquisitions shall not
                  exceed U.S.$250,000 in any calendar year; provided further,
                  however, that such repurchases and other acquisitions shall be
                  excluded in the calculation of the amount of Restricted
                  Payments under clause (a) (3) above;

            (5)   the repurchase of Warrant Shares pursuant to the terms of the
                  Warrant Agreement as in effect on the Issue Date;

            (6)   (A) any liquidation preference accrual or accretion with
                  respect to the New Preferred Shares or (B) any liquidation
                  preference payment made with respect to New Preferred Shares
                  in accordance with the rights and designations of such Capital
                  Stock as in effect on the Issue Date so long as the Company
                  has made a Put Offer pursuant to Section 4.15 herein within 60
                  days prior to payment of the liquidation preference with
                  respect to such New Preferred Shares; or

            (7)   payments or distributions to dissenting stockholders required
                  by applicable law, pursuant to or in connection with an Exit
                  Transaction that complies Section 5.01 hereof.

SECTION 4.08    Limitation on Restrictions on Distributions from Restricted
                Subsidiaries.

      The Company shall not, and shall not permit any Restricted Subsidiary to,
create or otherwise cause or permit to exist or become effective any consensual
encumbrance or restriction on the ability of any Restricted Subsidiary to (a)
pay dividends or make any other distributions

                                       45
<PAGE>

on its Capital Stock to the Company or a Restricted Subsidiary or pay any
Indebtedness owed to the Company, (b) make any loans or advances to the Company
or (c) transfer any of its property or assets to the Company, except:

            (1)   any encumbrance or restriction pursuant to an agreement in
                  effect at or entered into on the Issue Date;

            (2)   any encumbrance or restriction with respect to a Restricted
                  Subsidiary in existence at the time such Restricted Subsidiary
                  was acquired by the Company (other than Indebtedness Incurred
                  as consideration in, or to provide all or any portion of the
                  funds or credit support utilized to consummate, the
                  transaction or series of related transactions pursuant to
                  which such Restricted Subsidiary became a Restricted
                  Subsidiary or was acquired by the Company) and outstanding on
                  such date;

            (3)   any encumbrance or restriction pursuant to an agreement
                  effecting a Refinancing of Indebtedness Incurred pursuant to
                  an agreement referred to in clause (1) or (2) of this Section
                  4.08 or this clause (3) or contained in any amendment to an
                  agreement referred to in clause (1) or (2) of this Section
                  4.08 or this clause (3); provided, however, that the
                  encumbrances and restrictions with respect to such Restricted
                  Subsidiary contained in any such refinancing agreement or
                  amendment are no less favorable to the Noteholders than
                  encumbrances and restrictions with respect to such Restricted
                  Subsidiary contained in such predecessor agreements;

            (4)   any such encumbrance or restriction consisting of customary
                  non-assignment provisions in concessions, permits, licensing
                  agreements and leases governing leasehold interests to the
                  extent such provisions restrict the transfer of the
                  concession, permit, license or lease or the rights granted or
                  property leased thereunder;

            (5)   in the case of clause (c) above, restrictions contained in
                  security agreements or mortgages securing Indebtedness of a
                  Restricted Subsidiary to the extent such restrictions restrict
                  the transfer of the property subject to such security
                  agreements or mortgages;

            (6)   any restriction with respect to a Restricted Subsidiary
                  imposed pursuant to an agreement entered into for the sale or
                  disposition of all or substantially all the Capital Stock or
                  assets of such Restricted Subsidiary pending the closing of
                  such sale or disposition;

            (7)   any restriction on the sale or other disposition of assets or
                  property securing Indebtedness as a result of a Permitted Lien
                  on such assets or property;

            (8)   an encumbrance or restriction pursuant to purchase money
                  obligations for property acquired in the ordinary course of
                  business that impose

                                       46
<PAGE>

                  restrictions of the nature described in clause (c) above on
                  the property so acquired;

            (9)   any encumbrance or restriction existing under or by reason of
                  applicable law or regulations;

            (10)  customary provisions relating to assets or properties in which
                  the Company has Investments in joint ventures, provided that
                  the Company was entitled to make the Investment pursuant to
                  Section 4.07 hereof; and

            (11)  any encumbrance or restriction existing by reason of any
                  Purchase Money Note or other Indebtedness or contractual
                  requirements incurred with respect to a Qualified
                  Securitization Transaction relating to a Qualified Subsidiary.

SECTION 4.09    Limitation on Indebtedness.

      (a) The Company shall not, and shall not permit any Restricted Subsidiary
to, Incur, directly or indirectly, any Indebtedness; provided, however, that the
Company shall be entitled to Incur Indebtedness if, on the date of such
Incurrence and after giving effect thereto no Default has occurred and is
continuing and,

      (1) the Consolidated Leverage Ratio would be less than 3.75 to 1; and

      (2) the Fixed Charge Coverage Ratio would be at least 2.0 to 1.0.

      (b) Notwithstanding the foregoing paragraph (a), so long as no Default has
occurred and is continuing, the Company and the Restricted Subsidiaries will be
entitled to Incur any or all of the following Indebtedness:

            (1)   Indebtedness of the Company or a Restricted Subsidiary
                  Incurred at any time after the Issue Date for the purposes of
                  financing the cost (including the cost of design,
                  construction, acquisition, installation, development,
                  improvement or integration) of telecommunications assets
                  (including acquisitions by way of capital lease and
                  acquisitions of Capital Stock of a Person that becomes a
                  Restricted Subsidiary as a result of such acquisition to the
                  extent of the fair value of the telecommunications assets so
                  acquired), up to U.S.$100.0 million in aggregate principal
                  amount at any one time outstanding;

            (2)   Indebtedness owed to and held by the Company or a Wholly Owned
                  Subsidiary; provided, however, that (A) any subsequent
                  issuance or transfer of any Capital Stock which results in any
                  such Wholly Owned Subsidiary ceasing to be a Wholly Owned
                  Subsidiary or any subsequent transfer of such Indebtedness
                  (other than to the Company or a Wholly Owned Subsidiary) shall
                  be deemed, in each case, to constitute the Incurrence of such
                  Indebtedness by the obligor thereon and (B) if the Company or
                  any Guarantor is the obligor on such Indebtedness, such

                                       47
<PAGE>

                  Indebtedness is expressly subordinated to the prior payment in
                  full in cash of all obligations with respect to the Notes, in
                  the case of the Company or the Subsidiary Guarantee, in the
                  case of any Guarantor;

            (3)   Indebtedness with respect to (i) the Notes and the related
                  Subsidiary Guarantees, (ii) the Company's 13-3/4% Series B
                  Senior Notes due 2007 and any guarantees by Restricted
                  Subsidiaries made in connection therewith; and (iii) the
                  Company's Senior Notes due 2007 and any guarantees by
                  Restricted Subsidiaries made in connection therewith;

            (4)   Indebtedness outstanding on the Issue Date (other than
                  Indebtedness described in clause (2) or (3) of paragraph (b)
                  of this Section 4.09);

            (5)   Indebtedness of a Restricted Subsidiary Incurred and
                  outstanding on or prior to the date on which such Restricted
                  Subsidiary was acquired by the Company (other than
                  Indebtedness Incurred in connection with, or to provide all or
                  any portion of the funds or credit support utilized to
                  consummate, the transaction or series of related transactions
                  pursuant to which such Restricted Subsidiary became a
                  Restricted Subsidiary or was acquired by the Company);
                  provided, however, that on the date of such acquisition and
                  after giving pro forma effect thereto, the Company would have
                  been able to Incur at least U.S.$1.00 of additional
                  Indebtedness pursuant to paragraph (a) of this Section 4.09;

            (6)   Refinancing Indebtedness in respect of Indebtedness Incurred
                  pursuant to paragraph (a) or pursuant to clause (1), (3), (4),
                  (5) or this clause (6); provided, however, that to the extent
                  such Refinancing Indebtedness directly or indirectly
                  Refinances Indebtedness of a Subsidiary Incurred pursuant to
                  clause (5), such Refinancing Indebtedness shall be Incurred
                  only by such Subsidiary;

            (7)   Hedging Obligations that are Incurred for the purpose of
                  protecting the Company against fluctuations in interest rates
                  with respect to Indebtedness permitted to be Incurred by the
                  Company pursuant to this Indenture or against currency
                  fluctuations in the ordinary course of business; provided,
                  however, that the notional amount of any Hedging Obligations
                  under any Interest Rate Agreement shall not exceed the
                  principal amount of the Indebtedness appearing on the balance
                  sheet of the Company for which the Interest Rate Agreement has
                  been entered into and the aggregate notional amount of all
                  Hedging Obligations under Currency Agreements shall not exceed
                  U.S.$50.0 million at any one time outstanding;

            (8)   Indebtedness consisting of Subordinated Obligations owing to
                  any Persons that are not then Affiliates of the Company which
                  is Incurred by the Company or any Restricted Subsidiary up to
                  U.S. $25.0 million aggregate principal amount at any one time
                  outstanding; provided, however, that any Indebtedness Incurred
                  pursuant to this clause (8) shall not have a Stated

                                       48
<PAGE>

                  Maturity on or prior to the Stated Maturity of the Notes,
                  shall not be mandatorily redeemable, pursuant to a sinking
                  fund obligation or otherwise, or be redeemable at the option
                  of the holders thereof, in whole or in part, on or prior to
                  the Stated Maturity of the Notes and shall not pay principal
                  or interest in cash on or prior to the Stated Maturity of the
                  Notes;

            (9)   Indebtedness consisting of Subordinated Obligations owing to
                  any then Affiliates of the Company which is Incurred by the
                  Company or any Restricted Subsidiary up to U.S. $25.0 million
                  aggregate principal amount at any one time outstanding;
                  provided, however, that any Indebtedness Incurred pursuant to
                  this clause (9) shall not have a Stated Maturity on or prior
                  to the Stated Maturity of the Notes, shall not be mandatorily
                  redeemable, pursuant to a sinking fund obligation or
                  otherwise, or be redeemable at the option of the holders
                  thereof, in whole or in part, on or prior to the Stated
                  Maturity of the Notes, shall not pay principal or interest in
                  cash on or prior to the Stated Maturity of the Notes and shall
                  not accrete at a rate in excess of 18.0% per annum;

            (10)  Indebtedness consisting of performance and other similar bonds
                  and reimbursement obligations Incurred by the Company in the
                  ordinary course of business securing the performance of
                  contractual, franchise, concession or license obligations of
                  the Company or a Restricted Subsidiary;

            (11)  Indebtedness of the Company to the extent the net proceeds
                  thereof are promptly (i) used to purchase Notes pursuant to a
                  Put Offer or (ii) deposited to defease the Notes as described
                  under Article 8;

            (12)  Indebtedness arising from agreements providing for
                  indemnification, adjustment of purchase price or similar
                  obligations, from guarantees or from letters of credit, surety
                  bonds or performance bonds securing such obligations, of the
                  Company or its Restricted Subsidiaries, in any case Incurred
                  in connection with the disposition of any business, assets or
                  Restricted Subsidiary (other than guarantees of Indebtedness
                  Incurred by any Person acquiring all or any portion of such
                  business, assets or Restricted Subsidiary for the purpose of
                  financing such acquisition), in a principal amount not to
                  exceed the gross proceeds actually received by the Company or
                  a Restricted Subsidiary in connection with such disposition;

            (13)  Indebtedness of the Company or any Restricted Subsidiary
                  constituting reimbursement obligations with respect to letters
                  of credit issued in the ordinary course of business in respect
                  of workers' compensation claims or self-insurance, or other
                  Indebtedness with respect to reimbursement type obligations
                  regarding workers' compensation claims; provided, however,
                  that obligations arising upon the drawing of such letters of
                  credit or the Incurrence of such Indebtedness are reimbursed
                  within 30 days following such drawing or Incurrence;

                                       49
<PAGE>

            (14)  the guarantee by the Company or any of the Guarantors of
                  Indebtedness of the Company or a Restricted Subsidiary of the
                  Company that was permitted to be incurred by another provision
                  of this Section 4.09;

            (15)  Indebtedness equal to 100% of the Net Cash Proceeds received
                  by the Company or its Restricted Subsidiaries from the
                  issuance or sale of Capital Stock or capital contributions
                  subsequent to the Issue Date (other than pursuant to
                  irrevocable commitments made on or prior to the Issue Date or
                  an issuance or sale to a Subsidiary of the Company), except to
                  the extent such Net Cash Proceeds have been applied pursuant
                  to clause (a)(3)(B) of Section 4.07 hereof to make a
                  Restricted Payment;

            (16)  Attributable Debt with respect to any Sale/Leaseback
                  Transaction;

            (17)  Indebtedness Incurred in a Qualified Securitization
                  Transaction; and

            (18)  Indebtedness of the Company in an aggregate principal amount
                  which, when taken together with all other indebtedness of the
                  Company outstanding on the date of such Incurrence (other than
                  Indebtedness permitted by clauses (1) through (17) above or
                  paragraph (a)) does not exceed U.S.$20.0 million; provided
                  that such Indebtedness is used for working capital and/or
                  other general purposes.

      (c) Notwithstanding the foregoing, the Company shall not Incur any
Indebtedness pursuant to the foregoing paragraph (b) if the proceeds thereof are
used, directly or indirectly, to Refinance any Subordinated Obligations unless
such Indebtedness shall be subordinated to the Notes to at least the same extent
as such Subordinated Obligations.

      (d) Notwithstanding the foregoing, prior to the consummation of an Exit
Transaction, the Company shall not Incur any additional Indebtedness pursuant to
clauses (1), (3), (6), or (18) of paragraph (b) of this Section 4.09 (but, in
the case of clause (6), only with respect to Refinancing Indebtedness Incurred
pursuant to clauses (1) or (3) of paragraph (b) of this Section 4.09) if the
aggregate principal amount of Indebtedness of the Company and the Restricted
Subsidiaries at any one time outstanding pursuant to such clauses exceeds, or,
after giving effect to such additional Indebtedness, would exceed, U.S. $150
million. Simultaneously with the consummation of an Exit Transaction, this
paragraph (d) shall cease to be of any force or effect and shall not be
applicable to any Successor Company.

      (e) For purposes of determining compliance with this Section 4.09, in the
event that an item of Indebtedness meets the criteria of more than one of the
types of Indebtedness described above, the Company, in its sole discretion, will
(1) classify such item of Indebtedness at the time of Incurrence and only be
required to include the amount and type of such Indebtedness in one of the above
clauses and (2) be entitled to divide and classify an item of Indebtedness in
more than one of the types of Indebtedness described above.

                                       50
<PAGE>

SECTION 4.10    Limitation on Sales of Assets and Subsidiary Stock.

      (a) The Company shall not, and shall not permit any Restricted Subsidiary
to, directly or indirectly, consummate any Asset Disposition unless:

            (1)   the Company or such Restricted Subsidiary receives
                  consideration at the time of such Asset Disposition at least
                  equal to the fair market value (including as to the value of
                  all non-cash consideration), as determined in good faith by
                  the Board of Directors, of the shares and assets subject to
                  such Asset Disposition;

            (2)   at least 75% of the consideration thereof received by the
                  Company or such Restricted Subsidiary is in the form of cash
                  or cash equivalents;

            (3)   an amount equal to 100% of the Net Available Cash from such
                  Asset Disposition is applied by the Company (or such
                  Restricted Subsidiary, as the case may be) within one year
                  from the later of the date of such Asset Disposition or the
                  receipt of such Net Available Cash either:

                  (A)   to the extent the Company elects (or is required by the
                        terms of any Indebtedness), to prepay, repay, redeem or
                        purchase Senior Indebtedness of the Company or
                        Indebtedness (other than any Disqualified Stock) of a
                        Wholly Owned Subsidiary (in each case other than
                        Indebtedness owed to the Company or an Affiliate of the
                        Company); or

                  (B)   to the extent the Company elects, to acquire Additional
                        Assets;

            (4)   to the extent of the aggregate balance of Net Available Cash
                  after application in accordance with paragraph (3) above, the
                  Company or such Restricted Subsidiary makes an offer to the
                  Holders of the Notes (and to, at the election of the Company,
                  holders of other Senior Indebtedness designated by the
                  Company) to purchase Notes (and such other Senior
                  Indebtedness) pursuant to and subject to the conditions
                  contained in this Indenture; and

            (5)   to the extent that any portion of Net Available Cash remains
                  after compliance with clause (4) above, the Company or such
                  Restricted Subsidiary uses such remaining portion only for
                  purposes not prohibited in this Indenture.

      In connection with any prepayment, repayment or purchase of Indebtedness
pursuant to clause (A) of paragraph (3) or paragraph (4) above, the Company or
such Restricted Subsidiary shall permanently retire such Indebtedness and shall
cause the related loan commitment (if any) to be permanently reduced in an
amount equal to the principal amount so prepaid, repaid or purchased.

                                       51
<PAGE>

      Notwithstanding the foregoing provisions of this Section 4.10, the Company
and the Restricted Subsidiaries will not be required to apply any Net Available
Cash in accordance with this Section 4.10 except to the extent that the
aggregate Net Available Cash from all Asset Dispositions which are not applied
in accordance with this Section 4.10 exceeds U.S.$5.0 million. Pending
application of Net Available Cash pursuant to this Section 4.10 (except for
clause (a)(5) above), such Net Available Cash shall be invested in cash or
Temporary Cash Investments or applied to temporarily reduce revolving credit
Indebtedness.

      (b) For the purposes of this Section 4.10, the following are deemed to be
cash or cash equivalents:

            (1)   the assumption of Indebtedness of the Company or any
                  Restricted Subsidiary and the release of the Company or such
                  Restricted Subsidiary from all liability on such Indebtedness
                  in connection with such Asset Disposition; and

            (2)   securities received by the Company or any Restricted
                  Subsidiary from the transferee that are promptly converted by
                  the Company or such Restricted Subsidiary into cash.

SECTION 4.11    Limitations on Affiliate Transactions.

      (a) The Company shall not, and shall not permit any Restricted Subsidiary
to, enter into or permit to exist any transaction (including the purchase, sale,
lease or exchange of any property, employee compensation arrangements or the
rendering of any service) with, or for the benefit of, any Affiliate of the
Company (an "Affiliate Transaction") unless:

            (1)   the terms of the Affiliate Transaction are no less favorable
                  to the Company or such Restricted Subsidiary than those that
                  could be obtained at the time of the Affiliate Transaction in
                  arm's-length dealings with a Person who is not an Affiliate:,

            (2)   if such Affiliate Transaction involves an amount in excess of
                  U.S.$1.0 million but is less than or equal to U.S.$5.0
                  million, the terms of the Affiliate Transaction are set forth
                  in writing and a majority of disinterested directors of the
                  Company have determined in good faith that the criteria set
                  forth in clause (1) are satisfied and have approved the
                  relevant Affiliate Transaction as evidenced by a Board of
                  Directors resolution; and

            (3)   if such Affiliate Transaction involves an amount in excess of
                  U.S.$5.0 million, the Board of Directors shall also have
                  received a written opinion from an investment banking firm of
                  national United States prominence that is not an Affiliate of
                  the Company to the effect that such Affiliate Transaction is
                  fair, from a financial standpoint, to the Company and its
                  Restricted Subsidiaries.

      (b) The provisions of the preceding paragraph (a) will not apply to:

                                       52
<PAGE>

            (1)   any Investment (other than a Permitted Investment) or other
                  Restricted Payment, in each case permitted to be made pursuant
                  to Section 4.07 hereof;

            (2)   any issuance of securities, or other payments, awards or
                  grants in cash, securities or otherwise pursuant to, or the
                  funding of, employment arrangements, stock options and stock
                  ownership plans approved by a majority of the disinterested
                  members of the Board of Directors;

            (3)   loans or advances to employees in the ordinary course of
                  business in accordance with the past practices of the Company
                  or its Restricted Subsidiaries, but in any event not to exceed
                  U.S.$0.5 million in the aggregate outstanding at any one time;

            (4)   the payment of reasonable fees to directors of the Company and
                  its Restricted Subsidiaries who are not employees of the
                  Company or its Restricted Subsidiaries;

            (5)   any transaction with a Restricted Subsidiary or joint venture
                  or similar entity which would constitute an Affiliate
                  Transaction solely because the Company or a Restricted
                  Subsidiary owns an equity interest in or otherwise controls
                  such Restricted Subsidiary, joint venture or similar entity;

            (6)   the issuance or sale of any Capital Stock (other than
                  Disqualified Stock) of the Company;

            (7)   any Affiliate Transaction between the Company and a Wholly
                  Owned Subsidiary or between Wholly Owned Subsidiaries;

            (8)   any employment agreement entered into by the Company or any of
                  its Restricted Subsidiaries in the ordinary course of business
                  consistent with past practice; and

            (9)   transactions effected as part of a Qualified Securitization
                  Transaction, including, without limitation, any sale,
                  conveyance or other transfer of accounts receivable, contracts
                  receivable and other related assets customarily transferred in
                  an asset securitization transaction involving accounts
                  receivable or contracts receivable to a Qualified Subsidiary
                  in a Qualified Securitization Transaction.

SECTION 4.12    Limitations on Liens.

      The Company shall not, and shall not permit any Restricted Subsidiary to,
directly or indirectly, Incur or permit to exist any Lien of any nature
whatsoever on any of its properties (including Capital Stock of a Restricted
Subsidiary), whether owned at the Issue Date or thereafter acquired, other than
Permitted Liens, without effectively providing that the Notes or

                                       53
<PAGE>

the Subsidiary Guarantee, as applicable, shall be secured equally and ratably
with (or prior to) the obligations so secured for so long as such obligations
are so secured.

      Any Lien created for the benefit of the Holders of the Notes pursuant to
the preceding sentence shall provide by its terms that such Lien shall be
automatically and unconditionally released and discharged upon the release and
discharge of the initial Lien.

SECTION 4.13    Limitation of Business Activities.

      The Company shall not, and shall not permit any of its Restricted
Subsidiaries to, directly or indirectly, engage in any business other than the
Telecommunications Business.

SECTION 4.14    Corporate Existence.

      Subject to Article 5 hereof, the Company shall do or cause to be done all
things necessary to preserve and keep in full force and effect (i) its corporate
existence, and the corporate, partnership or other existence of each of its
Subsidiaries, in accordance with the respective organizational documents (as the
same may be amended from time to time) of the Company or any such Subsidiary and
(ii) the rights (charter and statutory), licenses and franchises of the Company
and its Subsidiaries; provided, however, that the Company shall not be required
to preserve any such right, license or franchise, or the corporate, partnership
or other existence of any of its Subsidiaries, if the Board of Directors shall
determine that the preservation thereof is no longer desirable in the conduct of
the business of the Company and its Subsidiaries, taken as a whole, and that the
loss thereof is not adverse in any material respect to the Holders of the Notes.

SECTION 4.15    Optional Offer to Repurchase Notes.

      Upon the occurrence of a Put Offer Event, each Holder shall have the right
to require that the Company offer to repurchase all or any part (equal to
U.S.$1.00 or an integral multiple thereof) of such Holder's Notes at a purchase
price in cash equal to 100% of the principal amount of such Notes plus accrued
and unpaid interest, if any, on the date of purchase and Additional Amounts, if
any, to the date of purchase (subject to the right of Holders of record on the
relevant record date to receive interest due on the relevant interest payment
date). The Put Offer, if any, will remain open for a period of at least 30 days
following its commencement but no longer than 60 days, except to the extent that
a longer period is required by applicable law (the "Put Offer Period"). On the
first Business Day after the termination of the Put Offer Period (the "Put
Payment Date"), the Company will purchase all Notes validly tendered and not
properly withdrawn pursuant to the Put Offer. Payment for any Notes so purchased
will be made in the same manner as interest payments are made on the Notes.

      Within 30 days following any Put Offer Event, the Company shall mail a
notice to each Holder with a copy to the Trustee (the "Put Offer") stating:

      (1)   that a Put Offer Event has occurred and that such Holder has the
            right to require the Company to purchase such Holder's Notes at a
            purchase price in cash equal to 100% of the principal amount thereof
            on the date of purchase, plus accrued and unpaid interest, if any,
            and Additional Amounts, if any, (the "Put Purchase

                                       54
<PAGE>

            Price") to the Put Payment Date (subject to the right of holders of
            record on the relevant record date to receive interest on the
            relevant interest payment date);

      (2)   the circumstances and relevant facts regarding such Put Offer Event
            (including information with respect to pro forma historical income,
            cash flow and capitalization after giving effect to such Put Offer
            Event);

      (3)   the Put Payment Date (which shall be no earlier than 30 days nor
            later than 60 days from the date such notice is mailed);

      (4)   that any Note accepted for payment pursuant to the Put Offer (and
            duly paid for on the Put Payment Date) shall cease to accrue
            interest and Additional Amounts, if applicable, after the Put
            Payment Date;

      (5)   that any Notes (or portions thereof) not validly tendered shall
            continue to accrue interest and Additional Amounts, if applicable;

      (6)   the instructions, as determined by the Company, consistent with the
            covenant described hereunder, that a Holder must follow in order to
            have its Notes purchased.

      On or before the Put Payment Date, if any, the Company shall, to the
extent lawful, (1) accept for payment all Notes or portions thereof validly
tendered and not properly withdrawn pursuant to the Put Offer, (2) deposit by
10:00 a.m., New York City time, on such date with the Paying Agent an amount
equal to the Put Purchase Price in respect of all Notes or portions thereof so
validly tendered and not properly withdrawn and (3) deliver or cause to be
delivered to the Trustee the Notes so accepted together with an Officers'
Certificate stating the aggregate principal amount of Notes or portions thereof
being purchased by the Company. The Paying Agent shall promptly (but in any case
not later than five days after the Put Payment Date) mail to each Holder of
Notes so validly tendered and not properly withdrawn the Put Purchase Price for
such Notes.

      Upon surrender and cancellation of a Definitive Note that is purchased in
part pursuant to the Put Offer, the Company shall promptly issue and the Trustee
shall authenticate and mail (or cause to be transferred by book entry) to the
surrendering Holder of such Definitive Note, a new Definitive Note equal in
principal amount to the unpurchased portion of such surrendered Definitive Note;
provided that each such new Certificated Note shall be in a principal amount of
$1,000 or an integral multiple thereof.

      Upon surrender of the Global Note that is purchased in part pursuant to a
Put Offer, the Paying Agent shall forward the Global Note to the Trustee who
shall make a notation on Schedule A thereof to reduce the principal amount of
such Global Note to an amount equal to the unpurchased portion of such Global
Note, as provided in Section 2.06 hereof. The Company shall publicly announce
the results of the Put Offer on the Put Payment Date. For purposes of this
Section 4.15, the Trustee shall act as the Paying Agent.

      The Company shall not be required to make a Put Offer following a Put
Offer Event if a third party makes the Put Offer in the manner, at the times and
otherwise in compliance with the

                                       55
<PAGE>

requirements set forth in this Indenture applicable to a Put Offer made by the
Company and purchases all Notes validly tendered and not withdrawn under such
Put Offer.

      The Company shall comply, to the extent applicable, with the requirements
of Section 14(e) of the Exchange Act and any other securities laws or
regulations in connection with the repurchase of Notes as a result of a Put
Offer Event. To the extent that the provisions of any securities laws or
regulations conflict with the provisions of the covenant described hereunder,
the Company shall comply with the applicable securities laws and regulations and
shall not be deemed to have breached its obligations under the covenant
described hereunder by virtue of its compliance with such securities laws or
regulations.

SECTION 4.16    [Intentionally Omitted].

SECTION 4.17    Limitation on the Sale or Issuance of Capital Stock of
                Restricted Subsidiaries.

      The Company

      (1)   shall not, and shall not permit any Restricted Subsidiary to, sell,
            lease, transfer or otherwise dispose of any Capital Stock of any
            Restricted Subsidiary to any Person (other than the Company or a
            Wholly Owned Subsidiary), and

      (2)   will not permit any Restricted Subsidiary to issue any of its
            Capital Stock (other than, if necessary, shares of its Capital Stock
            constituting directors' or other legally required qualifying shares)
            to any Person (other than to the Company or a Wholly Owned
            Subsidiary), unless:

            (A)   immediately after giving effect to such issuance, sale or
                  other disposition, neither the Company nor any of its
                  Subsidiaries own any Capital Stock of such Restricted
                  Subsidiary; or

            (B)   immediately after giving effect to such issuance, sale or
                  other disposition, such Restricted Subsidiary would no longer
                  constitute a Restricted Subsidiary and any Investment in such
                  Person remaining after giving effect thereto would have been
                  permitted to be made under Section 4.07 hereof if made on the
                  date of such issuance, sale or other disposition.

SECTION 4.18    Future Subsidiary Guarantors.

      The Company shall cause each future Restricted Subsidiary to promptly
Guarantee the Notes and execute a Supplemental Indenture providing for such
Subsidiary Guarantee on the terms and conditions set forth in this Indenture and
deliver an opinion of counsel satisfactory to the Trustee within 10 Business
Days of the date it was acquired or created. The form of such Supplemental
Indenture is attached as Exhibit C hereto.

                                       56
<PAGE>

SECTION 4.19    Additional Amounts.

      All payments made on or with respect to the Notes shall be made free and
clear of, and without withholding or deduction for or on account of any present
or future tax, duty, levy, impost, assessment or other governmental charge
imposed or levied by or on behalf of Mexico or any of its related political
subdivisions or taxing authorities (or by the jurisdiction of incorporation,
seat of management or residence for tax purposes of any successor to the Company
(a "Successor Jurisdiction")), including any related interest, penalties or
additions ("Taxes"), unless the Company is (or any other entity, on the
Company's behalf, is) required by law or by the interpretation of administration
of law.

      If the Company is required to withhold or deduct any amount for or on
account of Taxes from any payment made on or with respect to the Notes, the
Company shall pay such additional amounts ("Additional Amounts") as may be
necessary so that the net amount received by each Holder of the Notes after such
withholding or deduction (including withholding or deduction imposed upon such
Additional Amounts) will not be less than the amount such Holder would have
received if such Taxes had not been withheld or deducted.

      However, no Additional Amounts shall be payable with respect to:

      (1)   any Taxes which are imposed solely by reason of a present or former
            connection between the Holder or beneficial owner of the Note (or
            between a fiduciary, settlor, beneficiary, member of, or possessor
            of power over, such Holder or beneficial owner, if such Holder or
            beneficial owner is an estate, trust or partnership) and the
            jurisdiction imposing such Taxes, other than a connection arising
            from the mere holding of, or receipt of payments on, the Notes or by
            exercising any rights under the Notes or this Indenture;

      (2)   any Taxes to the extent they are imposed solely by reason of the
            failure by the Holder or beneficial owner to comply with any
            certification, identification, documentation or other reporting
            requirements, whether imposed by statute, applicable tax treaty,
            regulation or administrative practice; provided that

            (A)   such compliance is required or imposed as a precondition to
                  exemption from, or reduction in the rate of, such Taxes,

            (B)   such Holder may legally comply with such requirements, and

            (C)   at least 60 days prior to the first payment date with respect
                  to which the Company applies this clause (2) (or in the event
                  of any subsequent change in any such requirements, at least 60
                  days prior to the first payment date for which such change is
                  effective) the Company has notified the Trustee and all
                  Holders of the Notes in writing as to any such requirements;
                  or

      (3)   where presentation is required for payment on a Note, any Taxes
            which are imposed solely by reason of the Holder's presentation of a
            Note for payment more than 30 days after the date on which the
            relevant payment is first made available to the Holder (but only to
            the extent that the Holder would have been entitled to

                                       57
<PAGE>

            Additional Amounts had the Note been presented on any day (including
            the last day within such 30-day period);

      (4)   any estate, inheritance, gift, sales, transfer, personal property or
            similar Taxes imposed with respect to any Note;

      (5)   any Taxes that are only payable other than by withholding of
            deduction; or

      (6)   any combination of (1), (2), (3), (4) or (5) (the Taxes described in
            (1) through (6) for which no Additional Amounts are payable are
            hereinafter referred to as "Excluded Taxes").

      Notwithstanding the foregoing, the limitations on the Company's obligation
to pay Additional Amounts set forth in clause (2) above will not apply if:

            (i) the provision of information, documentation or other evidence
      described in such clause (2) would be materially more onerous, in form, in
      procedure or in the substance of information disclosed, to a Holder or
      beneficial owner of a Note than comparable information or other reporting
      requirements imposed under US tax law (including the United States --
      Mexico Income Tax Treaty), regulation and administrative practice (such as
      IRS Forms W-8 and W-9); or

            (ii) Rule 3.23.8 issued by the Secretaria de Hacienda y Credito
      Publico (Ministry of Finance and Public Credit) on April 30, 2004 or a
      substantially similar successor of such rule is in effect, unless (a) the
      provision of the information, documentation or other evidence described in
      clause (2) is expressly required by statute, regulation, ruling or
      administrative practice in order to apply Rule 3.23.8 (or successor rule),
      the Company cannot obtain such information, documentation or other
      evidence on its own through reasonable diligence and the Company otherwise
      would meet the requirements for application of Rule 3.23.8 (or successor
      rule) or (b) in the case of a Holder or beneficial owner of a Note that is
      a pension fund or other tax-exempt organization, payments to such Holder
      or beneficial owner would be subject to Taxes at a rate less than that
      provided by Rule 3.23.8 (or successor rule) if the information,
      documentation or other evidence required under clause (2) above were
      provided.

      In addition, clause (2) above shall be construed to require that a
non-Mexican pension or retirement fund or other Holder or beneficial owner of a
Note register with the Ministry of Finance and Public Credit of Mexico for the
purpose of establishing eligibility for an exemption from or reduction of Taxes.

      The Company shall make any required withholding or deduction and remit the
full amount deducted or withheld to the appropriate taxing authority, as and
when required by applicable law. The Company shall furnish to the Trustee,
within 30 days after the date the payment of any Taxes is due, evidence of such
payment by the Company. The Company shall deliver copies of such evidence to
Holders of the Notes or the Paying Agent upon request.

      The Company shall indemnify and hold harmless each Holder of Notes and,
upon written request of any Holder of Notes, reimburse each such Holder, for the
amount of:

                                       58
<PAGE>

      (1)   any Taxes (other than Excluded Taxes) levied or imposed and paid by
            such Holder as a result of payments made on or with respect to the
            Notes; provided that reasonable supporting documentation is
            provided; and

      (2)   any Taxes (other than Excluded Taxes) levied or imposed with respect
            to any reimbursement under the foregoing clause (1), so that the net
            amount received by such Holder after such reimbursement will not be
            less than the net amount the Holder would have received if Taxes
            (other than Excluded Taxes) on such reimbursement had not been
            imposed.

Any payments made pursuant to the preceding sentence shall be treated as
Additional Amounts for all relevant purposes.

      The Company shall pay any present or future stamp, court, documentary or
other similar Taxes, charges or levies that arise in Mexico or any of its
political Subdivisions (or any Successor Jurisdiction) from the execution,
delivery, registration of, or enforcement of rights under, the Notes, this
Indenture or any related document.

      Whenever in this Indenture or any related document there is mentioned, in
any context, the payment of principal (and premium, if any), redemption price,
interest or any other amount payable on or with respect to any Note such mention
shall be deemed to include any Additional Amounts to the extent that, in such
context, Additional Amounts are, were or would be payable in respect thereof.

      The obligation to pay Additional Amounts under the terms and conditions
described above shall survive any termination, defeasance or discharge of this
Indenture.

                                    ARTICLE 5

                                   SUCCESSORS

SECTION 5.01    Merger and Consolidation.

      (a) The Company shall not consolidate with or merge with or into, or
convey, transfer or lease, in one transaction or a series of transactions,
directly or indirectly, all or substantially all its assets to, any Person (an
"Exit Transaction"), unless one of the following conditions is satisfied (as may
be elected by the Company in its sole discretion):

      (i)   the Company offers to purchase each Holder's Notes pursuant to
            Section 4.15; or

      (ii)  each of the following conditions is satisfied:

            (1)   the resulting, surviving or transferee Person (the "Successor
                  Company") shall be a Person organized and existing under the
                  laws of Mexico, the United States of America, any State
                  thereof or the District of Columbia and the Successor Company
                  (if not the Company) shall expressly assume, by an indenture
                  supplemental thereto, executed and delivered to the

                                       59
<PAGE>

                  Trustee, in form satisfactory to the Trustee, all the
                  obligations of the Company under the Notes and this Indenture;

            (2)   immediately after giving pro forma effect to such transaction
                  (and treating any Indebtedness which becomes an obligation of
                  the Successor Company or any Subsidiary as a result of such
                  transaction as having been Incurred by such Successor Company
                  or such Subsidiary at the time of such transaction), no
                  Default shall have occurred and be continuing (provided that
                  for purposes of such pro forma analysis, Section 4.09(d) shall
                  be deemed to no longer be in force or effect);

            (3)   immediately after giving pro forma effect to such transaction,
                  one of the following two conditions is satisfied: either (i)
                  the Successor Company would be able to Incur an additional
                  U.S.$1.00 of Indebtedness pursuant to paragraph (a) of Section
                  4.09 hereof or (ii) both (A) the Consolidated Leverage Ratio
                  of the Successor Company is not more than the Consolidated
                  Leverage Ratio of the Company immediately prior to such
                  transaction and (B) the Fixed Charge Coverage Ratio of the
                  Successor Company is not less than the Fixed Charge Coverage
                  Ratio of the Company immediately prior to such transaction;

            (4)   immediately after giving pro forma effect to such transaction,
                  the Successor Company shall have Consolidated Net Worth in an
                  amount that is not less than the Consolidated Net Worth of the
                  Company immediately prior to such transaction; and

            (5)   the Company shall have delivered to the Trustee an Officers'
                  Certificate and an Opinion of Counsel, each stating that such
                  consolidation, merger or transfer and such supplemental
                  indenture (if any) comply with this Indenture (provided, that
                  such Opinion of Counsel may assume, among other things, the
                  satisfaction of all financial ratios in connection with such
                  transaction).

For purposes of calculating the Successor Company's Consolidated Leverage Ratio,
Fixed Charge Coverage Ratio and Consolidated Net Worth in this Section 5.01, all
references to the Company and its Restricted Subsidiaries in the definitions of
Consolidated Cash Flow, Consolidated Interest Expense, Consolidated Leverage
Ratio, Consolidated Net Income, Consolidated Net Worth and Fixed Charge Coverage
Ratio shall be deemed to include the Successor Company, the Company and its
Restricted Subsidiaries.

      (b) The Successor Company shall be the successor to the Company and shall
succeed to, and be substituted for, and may exercise every right and power of,
the Company under this Indenture, but the predecessor Company in the case of a
conveyance, transfer or lease shall not be released from the obligation to pay
the principal of and interest on the Notes unless such transaction (i) involves
a Successor Company other than the Company which expressly assumes, by an
indenture supplemental hereto, executed and delivered to the Trustee, in form
reasonably satisfactory to the Trustee, all of the obligations of the Company
under the Notes and this

                                       60
<PAGE>

Indenture and (ii) satisfies the other conditions set forth in Section
5.01(a)(ii), in which case the Company and each Guarantor will be released and
relieved of any and all obligations hereunder, under the Notes, any Subsidiary
Guarantee delivered in connection with this Indenture, and any other instrument,
undertaking or agreement delivered by the Company or a Guarantor in connection
with this Indenture (other than any Officers' Certificate). Upon delivery by the
Company to the Trustee of an Officers' Certificate to the effect that such
conveyance, transfer, or lease was made by the Company in accordance with the
provisions of this Indenture, including without limitation Section 5.01(a)(ii),
the Trustee shall execute any documents reasonably required in order to evidence
the release the Company and each Guarantor from their respective obligations
hereunder, under the Notes, under any Subsidiary Guarantee, and under any other
instrument, undertaking or agreement delivered by the Company or a Guarantor in
connection with this Indenture (other than any Officers' Certificate).

                                   ARTICLE 6

                              DEFAULTS AND REMEDIES

SECTION 6.01    Events of Default.

      An "Event of Default" occurs if:

      (a) the Company defaults in the payment when due of interest or any
Additional Amounts on the Notes and such default continues for a period of 30
days;

      (b) the Company defaults in the payment when due of principal of or
premium, if any, on the Notes when the same becomes due and payable at maturity,
upon redemption (including in connection with an Asset Sale Offer or a Put
Offer) or otherwise;

      (c) the Company fails to comply with any of the provisions of Section
5.01;

      (d) the Company fails to comply with the provisions of clause (c) of
Section 4.04 hereof for a period of 30 or more days commencing on the date of
such default;

      (e) the Company fails to comply with any of the provisions of Sections
4.07, 4.08, 4.09, 4.10 (other than a failure to purchase Notes), 4.03, 4.11,
4.12, 4.13, 4.15 (other than a failure to purchase Notes), 4.17, 4.18 or 4.19
for 30 days after notice to the Company by the Trustee or the Holders of at
least 25% in aggregate principal amount of the Notes then outstanding voting as
a single class;

      (f) the Company fails to observe or perform any other covenant,
representation, warranty or other agreement in this Indenture or the Notes for
60 days after notice to the Company by the Trustee or the Holders of at least
25% in aggregate principal amount of the Notes then outstanding voting as a
single class;

      (g) a default occurs under any mortgage, indenture or instrument under
which there may be issued or by which there may be secured or evidenced any
Indebtedness for money borrowed by the Company or any of its Significant
Subsidiaries, whether such Indebtedness or guarantee now exists, or is created
after the date of this Indenture, which default results in the acceleration

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of such Indebtedness prior to its express maturity and, in each case, the
principal amount of such Indebtedness exceeds U.S.$5.0 million or more;

      (h) a final judgment or decree for the payment of money is entered by a
court or courts of competent jurisdiction against the Company or any of its
Significant Subsidiaries or any group of Subsidiaries that, taken as a whole,
would constitute a Significant Subsidiary and such judgment or decree remains
undischarged for a period (during which execution shall not be effectively
stayed or waived within 10 days after notice to the Company by the Trustee or
the Holders of at least 25% in aggregate principal amount of the Notes then
outstanding voting as a single class) of 60 consecutive days, provided that such
undischarged judgment or decree exceeds U.S.$5.0 million;

      (i) the Company or any of its Significant Subsidiaries or any group of
Subsidiaries that, taken as a whole, would constitute a Significant Subsidiary
pursuant to or within the meaning of Bankruptcy Law:

            (i) commences a voluntary case,

            (ii) consents to the entry of an order for relief against it in an
      involuntary case,

            (iii) consents to the appointment of a custodian of it or for all or
      substantially all of its property,

            (iv) makes a general assignment for the benefit of its creditors, or

            (v) generally is not paying its debts as they become due;

      (j) a court of competent jurisdiction enters an order or decree under any
Bankruptcy Law that:

            (i) is for relief against the Company or any of its Significant
      Subsidiaries or any group of Subsidiaries that, taken as a whole, would
      constitute a Significant Subsidiary in an involuntary case;

            (ii) appoints a custodian of the Company or any of its Significant
      Subsidiaries or any group of Subsidiaries that, taken as a whole, would
      constitute a Significant Subsidiary or for all or substantially all of the
      property of the Company or any of its Significant Subsidiaries or any
      group of Subsidiaries that, taken as a whole, would constitute a
      Significant Subsidiary; or

            (iii) orders the liquidation of the Company or any of its
      Significant Subsidiaries or any group of Subsidiaries that, taken as a
      whole, would constitute a Significant Subsidiary;

and the order or decree remains unstayed and in effect for 60 consecutive days;
or

      (k) except as permitted by this Indenture, any Subsidiary Guarantee is
held in any final judicial proceeding to be unenforceable or invalid or shall
cease for any reason to be in full force

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<PAGE>

and effect or any Guarantor, or any Person acting on behalf of any Guarantor,
shall deny or disaffirm its obligations under such Guarantor's Subsidiary
Guarantee.

SECTION 6.02    Acceleration.

      If any Event of Default (other than an Event of Default specified in
clause (i) or (j) of Section 6.01 hereof with respect to the Company, any
Significant Subsidiary or any group of Significant Subsidiaries that, taken as a
whole, would constitute a Significant Subsidiary) occurs and is continuing, the
Trustee or the Holders of at least 25% in principal amount of the then
outstanding Notes may declare all the Notes to be due and payable immediately.
Upon such declaration, the Notes shall become due and payable immediately.
Notwithstanding the foregoing, if an Event of Default specified in clause (i) or
(j) of Section 6.01 hereof occurs with respect to the Company, any of its
Significant Subsidiaries or any group of Subsidiaries that, taken as a whole,
would constitute a Significant Subsidiary, all outstanding Notes shall be due
and payable immediately without further action or notice. The Holders of a
majority in aggregate principal amount of the then outstanding Notes by written
notice to the Trustee may on behalf of all of the Holders rescind an
acceleration and its consequences if the rescission would not conflict with any
judgment or decree and if all existing Events of Default (except nonpayment of
principal or premium, if any, that has become due solely because of the
acceleration) have been cured or waived.

SECTION 6.03    Other Remedies.

      If an Event of Default occurs and is continuing, the Trustee may pursue
any available remedy to collect the payment of principal, premium, if any,
interest and Additional Amounts, if any, on the Notes or to enforce the
performance of any provision of the Notes or this Indenture.

      The Trustee may maintain a proceeding even if it does not possess any of
the Notes or does not produce any of them in the proceeding. A delay or omission
by the Trustee or any Holder of a Note in exercising any right or remedy
accruing upon an Event of Default shall not impair the right or remedy or
constitute a waiver of or acquiescence in the Event of Default. All remedies are
cumulative to the extent permitted by law.

SECTION 6.04    Waiver of Past Defaults.

      Holders of not less than a majority in aggregate principal amount of the
then outstanding Notes by notice to the Trustee may on behalf of the Holders of
all of the Notes waive an existing Default or Event of Default and its
consequences hereunder, except a continuing Default or Event of Default in the
payment of the principal of, premium, if any, or interest and Additional
Amounts, if any, on, the Notes (including in connection with an offer to
purchase) (provided, however, that the Holders of a majority in aggregate
principal amount of the then outstanding Notes may rescind an acceleration and
its consequences, including any related payment default that resulted from such
acceleration). Upon any such waiver, such Default shall cease to exist, and any
Event of Default arising therefrom shall be deemed to have been cured for every
purpose of this Indenture; but no such waiver shall extend to any subsequent or
other Default or impair any right consequent thereon.

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<PAGE>

SECTION 6.05    Control by Majority.

      Holders of a majority in principal amount of the then outstanding Notes
may direct the time, method and place of conducting any proceeding for
exercising any remedy available to the Trustee or exercising any trust or power
conferred on it. However, the Trustee may refuse to follow any direction that
conflicts with law or this Indenture that the Trustee determines may be unduly
prejudicial to the rights of other Holders of Notes or that may involve the
Trustee in personal liability.

SECTION 6.06    Limitation on Suits.

      Except to enforce the right to receive payment of principal, premium (if
any) or interest when due, no Holder of a Note may pursue a remedy with respect
to this Indenture or the Notes only unless:

      (a) the Holder of a Note gives to the Trustee written notice of a
continuing Event of Default;

      (b) the Holders of at least 25% in principal amount of the then
outstanding Notes make a written request to the Trustee to pursue the remedy;

      (c) such Holder of a Note or Holders of Notes offer and, if requested,
provide to the Trustee indemnity satisfactory to the Trustee against any loss,
liability or expense;

      (d) the Trustee does not comply with the request within 60 days after
receipt of the request and the offer and, if requested, the provision of
indemnity; and

      (e) during such 60-day period the Holders of a majority in principal
amount of the then outstanding Notes do not give the Trustee a direction
inconsistent with the request.

      A Holder of a Note may not use this Indenture to prejudice the rights of
another Holder of a Note or to obtain a preference or priority over another
Holder of a Note.

SECTION 6.07    Rights of Holders of Notes to Receive Payment.

      Notwithstanding any other provision of this Indenture, the right of any
Holder of a Note to receive payment of principal, premium, if any, interest and
Additional Amounts, if any, on the Note, on or after the respective due dates
expressed in the Note (including in connection with an offer to purchase), or to
bring suit for the enforcement of any such payment on or after such respective
dates, shall not be impaired or affected without the consent of such Holder.

SECTION 6.08    Collection Suit by Trustee.

      If an Event of Default specified in Section 6.01(a) or (b) occurs and is
continuing, the Trustee is authorized to recover judgment in its own name and as
trustee of an express trust against the Company for the whole amount of
principal of, premium, if any, interest and Additional Amounts, if any,
remaining unpaid on the Notes and interest on overdue principal and, to the
extent lawful, interest and such further amount as shall be sufficient to cover
the costs

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<PAGE>

and expenses of collection, including the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel.

SECTION 6.09    Trustee May File Proofs of Claim.

      The Trustee is authorized to file such proofs of claim and other papers or
documents as may be necessary or advisable in order to have the claims of the
Trustee (including any claim for the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel) and the
Holders of the Notes allowed in any judicial proceedings relative to the Company
(or any other obligor upon the Notes), its creditors or its property and shall
be entitled and empowered to collect, receive and distribute any money or other
property payable or deliverable on any such claims and any custodian in any such
judicial proceeding is hereby authorized by each Holder to make such payments to
the Trustee, and in the event that the Trustee shall consent to the making of
such payments directly to the Holders, to pay to the Trustee any amount due to
it for the reasonable compensation, expenses, disbursements and advances of the
Trustee, its agents and counsel, and any other amounts due the Trustee under
Section 7.07 hereof. To the extent that the payment of any such compensation,
expenses, disbursements and advances of the Trustee, its agents and counsel, and
any other amounts due the Trustee under Section 7.07 hereof out of the estate in
any such proceeding, shall be denied for any reason, payment of the same shall
be secured by a Lien on, and shall be paid out of, any and all distributions,
dividends, money, securities and other properties that the Holders may be
entitled to receive in such proceeding whether in liquidation or under any plan
of reorganization or arrangement or otherwise. Nothing herein contained shall be
deemed to authorize the Trustee to authorize or consent to or accept or adopt on
behalf of any Holder any plan of reorganization, arrangement, adjustment or
composition affecting the Notes or the rights of any Holder, or to authorize the
Trustee to vote in respect of the claim of any Holder in any such proceeding.

SECTION 6.10    Priorities.

      If the Trustee collects any money pursuant to this Article, it shall pay
out the money in the following order:

            First: to the Trustee, its agents and attorneys for amounts due
      under Section 7.07 hereof, including payment of all compensation, expense
      and liabilities incurred, and all advances made, by the Trustee and the
      costs and expenses of collection;

            Second: to Holders of Notes for amounts due and unpaid on the Notes
      for principal, premium and Additional Amounts, if any, and interest,
      ratably, without preference or priority of any kind, according to the
      amounts due and payable on the Notes for principal, premium, if any and
      interest and Additional Amounts, if any, respectively; and

            Third: to the Company or to such party as a court of competent
      jurisdiction shall direct.

      The Trustee may fix a record date and payment date for any payment to
Holders of Notes pursuant to this Section 6.10.

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<PAGE>

SECTION 6.11    Undertaking for Costs.

      In any suit for the enforcement of any right or remedy under this
Indenture or in any suit against the Trustee for any action taken or omitted by
it as a Trustee, a court in its discretion may require the filing by any party
litigant in the suit of an undertaking to pay the costs of the suit, and the
court in its discretion may assess reasonable costs, including reasonable
attorneys' fees, against any party litigant in the suit, having due regard to
the merits and good faith of the claims or defenses made by the party litigant.
This Section does not apply to a suit by the Trustee, a suit by a Holder of a
Note pursuant to Section 6.07 hereof, or a suit by Holders of more than 10% in
principal amount of the then outstanding Notes.

                                    ARTICLE 7

                                     TRUSTEE

SECTION 7.01    Duties of Trustee.

      (a) If an Event of Default has occurred and is continuing, the Trustee
shall exercise such of the rights and powers vested in it by this Indenture, and
use the same degree of care and skill in its exercise, as a prudent person would
exercise or use under the circumstances in the conduct of such person's own
affairs.

      (b) Except during the continuance of an Event of Default:

            (i) the duties of the Trustee shall be determined solely by the
      express provisions of this Indenture and the Trustee need perform only
      those duties that are specifically set forth in this Indenture and no
      others, and no implied covenants or obligations shall be read into this
      Indenture against the Trustee; and

            (ii) in the absence of bad faith on its part, the Trustee may
      conclusively rely, as to the truth of the statements and the correctness
      of the opinions expressed therein, upon certificates or opinions furnished
      to the Trustee and conforming to the requirements of this Indenture.
      However, the Trustee shall examine the certificates and opinions to
      determine whether or not they conform to the requirements of this
      Indenture.

      (c) The Trustee may not be relieved from liabilities for its own negligent
action, its own negligent failure to act, or its own willful misconduct, except
that:

            (i) this paragraph does not limit the effect of paragraph (b) of
      this Section;

            (ii) the Trustee shall not be liable for any error of judgment made
      in good faith by a Responsible Officer, unless it is proved that the
      Trustee was negligent in ascertaining the pertinent facts; and

            (iii) the Trustee shall not be liable with respect to any action it
      takes or omits to take in good faith in accordance with a direction
      received by it pursuant to Section 6.05 hereof.

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<PAGE>

      (d) Whether or not therein expressly so provided, every provision of this
Indenture that in any way relates to the Trustee is subject to paragraphs (a),
(b), and (c) of this Section.

      (e) No provision of this Indenture shall require the Trustee to expend or
risk its own funds or incur any liability in the performance of any of its
duties hereunder or in the exercise of any of its rights or powers if it shall
have reasonable grounds to believe that repayment of such funds or adequate
indemnity against such risk or liability is not reasonably assured to it. The
Trustee shall be under no obligation to exercise any of its rights and powers
under this Indenture at the request of any Holders, unless such Holder shall
have offered to the Trustee security and indemnity satisfactory to it against
any loss, liability or expense.

      (f) The Trustee shall not be liable for interest on any money received by
it except as the Trustee may agree in writing with the Company. Money held in
trust by the Trustee need not be segregated from other funds except to the
extent required by law.

SECTION 7.02    Rights of Trustee.

      (a) The Trustee may conclusively rely upon any document believed by it to
be genuine and to have been signed or presented by the proper Person. The
Trustee need not investigate any fact or matter stated in the document.

      (b) Before the Trustee acts or refrains from acting, it may require an
Officers' Certificate and/or an Opinion of Counsel. The Trustee shall not be
liable for any action it takes or omits to take in good faith in reliance on
such Officers' Certificate or Opinion of Counsel. The Trustee may consult with
counsel of its selection and the advice of such counsel or any Opinion of
Counsel shall be full and complete authorization and protection from liability
in respect of any action taken, suffered or omitted by it hereunder in good
faith and in reliance thereon.

      (c) The Trustee may act through its attorneys, agents, other experts or
advisers and shall not be responsible for the misconduct or negligence of any
agent appointed with due care.

      (d) The Trustee shall not be liable for any action it takes or omits to
take in good faith that it believes to be authorized or within the rights or
powers; provided, however that the Trustee's conduct does not constitute willful
misconduct or negligence.

      (e) Unless otherwise specifically provided in this Indenture, any demand,
request, direction or notice from the Company shall be sufficient if signed by
an Officer of the Company.

      (f) The Trustee shall be under no obligation to exercise any of the rights
or powers vested in it by this Indenture at the request or direction of any of
the Holders unless such Holders shall have offered to the Trustee security or
indemnity satisfactory to it against the costs, expenses and liabilities that
might be incurred by it in compliance with such request or direction.

      (g) The Trustee shall not be deemed to have notice of any Default or Event
of Default unless a Responsible Officer of the Trustee has actual knowledge
thereof or unless written notice of any event which is in fact such a default is
received by the Trustee at the Corporate Trust Office of the Trustee, and such
notice references the Notes and this Indenture.

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<PAGE>

      (h) The rights, privileges, protections, immunities and benefits given to
the Trustee, including, without limitation, its right to be indemnified, are
extended to, and shall be enforceable by, the Trustee in each of its capacities
hereunder, and to each agent, custodian and other Person employed to act
hereunder.

      (i) The Trustee may request that the Company deliver an Officers'
Certificate setting forth the names of individuals and/or titles of officers
authorized at such time to take specified actions pursuant to this Indenture,
which Officers' Certificate may be signed by any person authorized to sign an
Officers' Certificate, including any person specified as so authorized in any
such certificate previously delivered and not superseded.

SECTION 7.03    Individual Rights of Trustee.

      The Trustee in its individual or any other capacity may become the owner
or pledgee of Notes and may otherwise deal with the Company or any Affiliate of
the Company with the same rights it would have if it were not Trustee. However,
in the event that the Trustee acquires any conflicting interest it must
eliminate such conflict within 90 days, apply to the SEC for permission to
continue as trustee or resign. Any Agent may do the same with like rights and
duties. The Trustee is also subject to Sections 7.10 and 7.11 hereof.

SECTION 7.04    Trustee's Disclaimer.

      The Trustee shall not be responsible for and makes no representation as to
the validity or adequacy of this Indenture or the Notes, it shall not be
accountable for the Company's use of the proceeds from the Notes or any money
paid to the Company or upon the Company's direction under any provision of this
Indenture, it shall not be responsible for the use or application of any money
received by any Paying Agent other than the Trustee, and it shall not be
responsible for any statement or recital herein or any statement in the Notes or
any other document in connection with the sale of the Notes or pursuant to this
Indenture other than its certificate of authentication.

SECTION 7.05    Notice of Defaults.

      If a Default or Event of Default occurs and is continuing and if the
Trustee has actual knowledge of it, the Trustee shall mail to Holders of Notes a
notice of the Default or Event of Default within 90 days after it occurs. Except
in the case of a Default or Event of Default in payment of principal of,
premium, if any, or interest on any Note, the Trustee shall be protected in
withholding such notice if and so long as the board of directors, the executive
committee or a trust committee of directors or Responsible Officers of the
Trustee in good faith determines that the withholding of such notice is in the
interest of the Holders of the Notes.

SECTION 7.06    Reports by Trustee to Holders of the Notes.

      Within 60 days after each February 15 beginning with the February 15
following the date of this Indenture, and for so long as Notes remain
outstanding, the Trustee shall mail to the Holders of the Notes a brief report
dated as of such reporting date that complies with TIA Section 313(a) (but if no
event described in TIA Section 313(a) has occurred within the twelve months
preceding the reporting date, no report need be transmitted). The Trustee also
shall comply with TIA Section 313(b)(2). The Trustee shall also transmit by mail
all reports as required by TIA Section 313(c).

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<PAGE>

      A copy of each report at the time of its mailing to the Holders of Notes
shall be mailed to the Company and filed with the SEC and each stock exchange on
which the Notes are listed in accordance with TIA Sections 313(d). The Company
shall promptly notify the Trustee when the Notes are listed or delisted on any
stock exchange.

SECTION 7.07    Compensation and Indemnity.

      The Company shall pay to the Trustee from time to time such compensation
for its acceptance of this Indenture and services hereunder as shall be agreed
upon in writing by the Company and the Trustee. The Trustee's compensation shall
not be limited by any law on compensation of a trustee of an express trust. The
Company shall reimburse the Trustee promptly upon request for all reasonable
disbursements, advances and expenses incurred or made by it in addition to the
compensation for its services. Such expenses shall include the reasonable
compensation, disbursements and expenses of the Trustee's agents and counsel.

      The Company shall indemnify the Trustee or any predecessor Trustee and
their agents against any and all losses, liabilities, damages, claims or
expenses, including taxes (other than taxes based upon, measured by or
determined by the income of the Trustee) incurred by it arising out of or in
connection with the acceptance or administration of its duties under this
Indenture, including the costs and expenses of enforcing this Indenture against
the Company (including this Section 7.07) and defending itself against any claim
(whether asserted by the Company or any Holder or any other person) or liability
in connection with the exercise or performance of any of its powers or duties
hereunder, except to the extent any such loss, liability, damage, claim or
expense may be attributable to its negligence or bad faith. The Trustee shall
notify the Company promptly of any claim for which it may seek indemnity.
Failure by the Trustee to so notify the Company shall not relieve the Company of
its obligations hereunder. The Company shall defend the claim and the Trustee
shall cooperate in the defense. The Trustee may have separate counsel and the
Company shall pay the reasonable fees and expenses of such counsel. The Company
need not pay for any settlement made without its consent, which consent shall
not be unreasonably withheld.

      The obligations of the Company under this Section 7.07 shall survive the
satisfaction and discharge of this Indenture and the resignation and removal of
the Trustee.

      To secure the Company's payment obligations in this Section, the Trustee
shall have a Lien prior to the Notes on all money or property held or collected
by the Trustee, except that held in trust to pay principal and interest on
particular Notes. Such Lien shall survive the satisfaction and discharge of this
Indenture.

      When the Trustee incurs expenses or renders services after an Event of
Default specified in Section 6.01(i) or (j) hereof occurs, the expenses and the
compensation for the services (including the fees and expenses of its agents and
counsel) are intended to constitute expenses of administration under any
Bankruptcy Law.

      The Trustee shall comply with the provisions of TIA Section 313(b)(2) to
the extent applicable.

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<PAGE>

SECTION 7.08    Replacement of Trustee.

      A resignation or removal of the Trustee and appointment of a successor
Trustee shall become effective only upon the successor Trustee's acceptance of
appointment as provided in this Section.

      The Trustee may resign in writing at any time and be discharged from the
trust hereby created by so notifying the Company. The Holders of a majority in
principal amount of the then outstanding Notes may remove the Trustee by so
notifying the Trustee and the Company in writing. The Company may remove the
Trustee if:

      (a) the Trustee fails to comply with Section 7.10 hereof;

      (b) the Trustee is adjudged a bankrupt or an insolvent or an order for
relief is entered with respect to the Trustee under any Bankruptcy Law;

      (c) a custodian or public officer takes charge of the Trustee or its
property; or

      (d) the Trustee becomes incapable of acting.

      If the Trustee resigns or is removed or if a vacancy exists in the office
of Trustee for any reason, the Company shall promptly appoint a successor
Trustee. Within one year after the successor Trustee takes office, the Holders
of a majority in principal amount of the then outstanding Notes may appoint a
successor Trustee to replace the successor Trustee appointed by the Company.

      If a successor Trustee does not take office within 60 days after the
retiring Trustee resigns or is removed, the retiring Trustee, the Company, or
the Holders of at least 10% in principal amount of the then outstanding Notes
may petition any court of competent jurisdiction at the expense of the Company
for the appointment of a successor Trustee.

      If the Trustee, after written request by any Holder who has been a Holder
for at least six months, fails to comply with Section 7.10, such Holder may
petition any court of competent jurisdiction at the expense of the Company for
the removal of the Trustee and the appointment of a successor Trustee.

      A successor Trustee shall deliver a written acceptance of its appointment
to the retiring Trustee and to the Company. Thereupon, the resignation or
removal of the retiring Trustee shall become effective, and the successor
Trustee shall have all the rights, powers and duties of the Trustee under this
Indenture. The successor Trustee shall mail a notice of its succession to
Holders. The retiring Trustee shall promptly transfer all property held by it as
Trustee to the successor Trustee, provided all sums owing to the Trustee
hereunder have been paid and subject to the Lien provided for in Section 7.07
hereof. Notwithstanding replacement of the Trustee pursuant to this Section
7.08, the Company's obligations under Section 7.07 hereof shall continue for the
benefit of the retiring Trustee.

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SECTION 7.09    Successor Trustee by Merger, etc.

      If the Trustee consolidates, merges or converts into, or transfers all or
substantially all of its corporate trust business to, another corporation, the
successor corporation without any further act shall be the successor Trustee.

SECTION 7.10    Eligibility; Disqualification.

      There shall at all times be a Trustee hereunder that is a corporation
organized and doing business under the laws of the United States of America or
of any state thereof that is authorized under such laws to exercise corporate
trustee power, that is subject to supervision or examination by federal or state
authorities and that has a combined capital and surplus of at least U.S.$50
million as set forth in its most recent published annual report of condition.

      This Indenture shall always have a Trustee who satisfies the requirements
of TIA Section 310(a)(1), (2) and (5). The Trustee is subject to TIA Section
310(b).

SECTION 7.11    Preferential Collection of Claims Against Company.

      The Trustee is subject to TIA Section 311(a), excluding any creditor
relationship listed in TIA Section 311(b). A Trustee who has resigned or been
removed shall be subject to TIA Section 311(a) to the extent indicated therein.

SECTION 7.12    Appointment of Co-Trustee.

      (a) Notwithstanding any other provisions of this Indenture, at any time,
for the purpose of meeting any legal requirement of any jurisdiction in which
any part of this Indenture may at the time be located, the Trustee shall have
the power and may execute and deliver all instruments necessary to appoint one
or more Persons to act as a co-trustee or co-trustees, or separate trustee or
separate trustees, of all or any part of this Indenture, and to vest in such
Person or Persons, in such capacity and for the benefit of the Noteholders, such
title to this Indenture, or any part hereof, and subject to the other provisions
of this Section 7.12, such powers, duties, obligations, rights and trusts as the
Trustee may consider necessary or desirable. No co-trustee or separate trustee
hereunder shall be required to meet the terms of eligibility as a successor
trustee under Section 7.10 and no notice to Noteholders of the appointment of
any co-trustee or separate trustee shall be required.

      (b) Every separate trustee and co-trustee shall, to the extent permitted
by law, be appointed and act subject to the following provisions and conditions:

            (i) all rights, powers, duties and obligations conferred or imposed
      upon the Trustee shall be conferred or imposed upon and exercised or
      performed by the Trustee and such separate trustee or co-trustee jointly
      (it being understood that such separate trustee or co-trustee is not
      authorized to act separately without the Trustee joining in such act),
      except to the extent that under any law of any jurisdiction in which any
      particular act or acts are to be performed the Trustee shall be
      incompetent or unqualified to perform such act or acts, in which event
      such rights, powers, duties and obligations (including the holding of
      title to this Indenture or any portion thereof in any such jurisdiction)
      shall be

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<PAGE>

      exercised and performed singly by such separate trustee or co-trustee, but
      solely at the direction of the Trustee;

            (ii) no trustee hereunder shall be personally liable by reason of
      any act or omission of any other trustee hereunder; and

            (iii) the Trustee may at any time accept the resignation of or
      remove any separate trustee or co-trustee.

      (c) Any notice, request or other writing given to the Trustee shall be
deemed to have been given to each of the then separate trustees and co-trustees,
as effectively as if given to each of them. Every instrument appointing any
separate trustee or co-trustee shall refer to this Indenture and the conditions
of this Section 7.12. Each separate trustee and co-trustee, upon its acceptance
of the trusts conferred, shall be vested with the estates or property specified
in its instrument of appointment, either jointly with the Trustee or separately,
as may be provided therein, subject to all the provisions of this Indenture,
specifically including every provision of this Indenture relating to the conduct
of, affecting the liability of, or affording protection or rights (including the
rights to compensation, reimbursement and indemnification hereunder) to, the
Trustee. Every such instrument shall be filed with the Trustee.

      (d) Any separate trustee or co-trustee may at any time constitute the
Trustee its agent or attorney-in-fact with full power and authority, to the
extent not prohibited by law, to do any lawful act under or in respect of this
Indenture on its behalf and in its name. If any separate trustee or co-trustee
shall die, become incapable of acting, resign or be removed, all of its estates,
properties, rights, remedies and trusts shall vest in and be exercised by the
Trustee, to the extent permitted by law, without the appointment of a new or
successor trustee.

                                    ARTICLE 8

                    LEGAL DEFEASANCE AND COVENANT DEFEASANCE

SECTION 8.01    Option to Effect Legal Defeasance or Covenant Defeasance.

      The Company may, at the option of its Board of Directors evidenced by a
resolution set forth in an Officers' Certificate, at any time, elect to have
either Section 8.02 or 8.03 hereof be applied to all outstanding Notes upon
compliance with the conditions set forth below in this Article 8.

SECTION 8.02    Legal Defeasance and Discharge.

      Upon the Company's exercise under Section 8.01 hereof of the option
applicable to this Section 8.02, the Company shall, subject to the satisfaction
of the conditions set forth in Section 8.04 hereof, be deemed to have been
discharged from its obligations with respect to all outstanding Notes on the
date the conditions set forth below are satisfied (hereinafter, "Legal
Defeasance"). For this purpose, Legal Defeasance means that the Company shall be
deemed to have paid and discharged the entire Indebtedness represented by the
outstanding Notes, which shall thereafter be deemed to be "outstanding" only for
the purposes of Section 8.05 hereof and the other Sections of this Indenture
referred to in (a) and (b) below, and to have satisfied all its

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other obligations under such Notes and this Indenture (and the Trustee, on
demand of and at the expense of the Company, shall execute proper instruments
acknowledging the same), except for the following provisions which shall survive
until otherwise terminated or discharged hereunder: (a) the rights of Holders of
outstanding Notes to receive solely from the trust fund described in Section
8.04 hereof, and as more fully set forth in such Section, payments in respect of
the principal of, premium, if any, and interest on such Notes when such payments
are due, (b) the Company's obligations with respect to such Notes under Article
2 and Sections 4.02 and Section 4.20 hereof, (c) the rights, powers, trusts,
duties and immunities of the Trustee hereunder and the Company's obligations in
connection therewith and (d) this Article 8. Subject to compliance with this
Article 8, the Company may exercise its option under this Section 8.02
notwithstanding the prior exercise of its option under Section 8.03 hereof.

SECTION 8.03    Covenant Defeasance.

      Upon the Company's exercise under Section 8.01 hereof of the option
applicable to this Section 8.03, the Company shall, subject to the satisfaction
of the conditions set forth in Section 8.04 hereof, be released from its
obligations under the covenants contained in Sections 4.03, 4.07, 4.08, 4.09,
4.10, 4.11, 4.12, 4.13, 4.15, 4.17 and 4.18 hereof and clauses (3) and (4) of
Section 5.01(a) hereof with respect to the outstanding Notes on and after the
date the conditions set forth in Section 8.04 are satisfied (hereinafter,
"Covenant Defeasance"), and the Notes shall thereafter be deemed not
"outstanding" for the purposes of any direction, waiver, consent or declaration
or act of Holders (and the consequences of any thereof) in connection with such
covenants, but shall continue to be deemed "outstanding" for all other purposes
hereunder (it being understood that such Notes shall not be deemed outstanding
for accounting purposes). For this purpose, Covenant Defeasance means that, with
respect to the outstanding Notes, the Company may omit to comply with and shall
have no liability in respect of any term, condition or limitation set forth in
any such covenant, whether directly or indirectly, by reason of any reference
elsewhere herein to any such covenant or by reason of any reference in any such
covenant to any other provision herein or in any other document and such
omission to comply shall not constitute a Default or an Event of Default under
Section 6.01 hereof, but, except as specified above, the remainder of this
Indenture and such Notes shall be unaffected thereby. In addition, upon the
Company's exercise under Section 8.01 hereof of the option applicable to this
Section 8.03 hereof, subject to the satisfaction of the conditions set forth in
Section 8.04 hereof, Sections 6.01(c) (but only with respect to Section 4.04 or
to clauses (3) and (4) of Section 5.01(a)), 6.01(e) (other than with respect to
Section 4.19), 6.01(g), 6.01(h) and 6.01(i) hereof shall not constitute Events
of Default.

SECTION 8.04    Conditions to Legal or Covenant Defeasance.

      The following shall be the conditions to the application of either Section
8.02 or 8.03 hereof to the outstanding Notes:

      In order to exercise either Legal Defeasance or Covenant Defeasance:

      (a) the Company must irrevocably deposit with the Trustee, in trust, for
the benefit of the Holders, cash in United States dollars, non-callable
Government Securities, or a combination thereof, in such amounts as will be
sufficient, in the opinion of a nationally recognized firm of

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independent public accountants, to pay the principal of, premium and Additional
Interest, if any, and interest on the outstanding Notes on the stated date for
payment thereof or on the applicable redemption date, as the case may be;

      (b) in the case of an election under Section 8.02 hereof, the Company
shall have delivered to the Trustee (i) an Opinion of Counsel in the United
States reasonably acceptable to the Trustee confirming that (A) the Company has
received from, or there has been published by, the Internal Revenue Service a
ruling or (B) since the date of this Indenture, there has been a change in the
applicable federal income tax law, in either case to the effect that, and based
thereon such Opinion of Counsel shall confirm that, the Holders of the
outstanding Notes will not recognize income, gain or loss for federal income tax
purposes as a result of such Legal Defeasance and will be subject to federal
income tax on the same amounts, in the same manner and at the same times as
would have been the case if such Legal Defeasance had not occurred and (ii) an
Opinion of Counsel in Mexico reasonably acceptable to the Trustee confirming
that Holders of the Notes will not recognize income, gain or loss for Mexican
taxes purposes as a result of such Legal Defeasance and will be subject to
Mexican taxes (including withholding taxes) on the same amounts, in the same
manner and at the same times as would have been the case if such Legal
Defeasance had not occurred;

      (c) in the case of an election under Section 8.03 hereof, the Company
shall have delivered to the Trustee (i) an Opinion of Counsel in the United
States reasonably acceptable to the Trustee confirming that the Holders of the
outstanding Notes will not recognize income, gain or loss for federal income tax
purposes as a result of such Covenant Defeasance and will be subject to federal
income tax on the same amounts, in the same manner and at the same times as
would have been the case if such Covenant Defeasance had not occurred and (ii)
an Opinion of Counsel in Mexico reasonably acceptable to the Trustee confirming
that Holders of the Notes will not recognize income, gain or loss for Mexican
taxes purposes as a result of such Covenant Defeasance and will be subject to
Mexican taxes (including withholding taxes) on the same amounts, in the same
manner and at the same times as would have been the case if such Covenant
Defeasance had not occurred;

      (d) no Default or Event of Default shall have occurred and be continuing
on the date of such deposit (other than a Default or Event of Default resulting
from the incurrence of Indebtedness all or a portion of the proceeds of which
will be used to defease the Notes pursuant to this Article 8 concurrently with
such incurrence) or insofar as Sections 6.01(i) or 6.01(j) hereof is concerned,
at any time in the period ending on the 91st day after the date of deposit;

      (e) such Legal Defeasance or Covenant Defeasance shall not result in a
breach or violation of, or constitute a default under, any material agreement or
instrument (other than this Indenture) to which the Company or any of its
Subsidiaries is a party or by which the Company or any of its Subsidiaries is
bound;

      (f) the Company shall have delivered to the Trustee an Opinion of Counsel
in the United States and Mexico (which may be subject to customary exceptions)
to the effect that on the 91st day following the deposit, the trust funds will
not be subject to the effect of any applicable bankruptcy, insolvency,
reorganization or similar laws affecting creditors' rights generally;

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      (g) the Company shall have delivered to the Trustee an Officers'
Certificate stating that the deposit was not made by the Company with the intent
of preferring the Holders over any other creditors of the Company or with the
intent of defeating, hindering, delaying or defrauding any other creditors of
the Company; and

      (h) the Company shall have delivered to the Trustee an Officers'
Certificate and an Opinion of Counsel in the United States and Mexico, each
stating that all conditions precedent provided for or relating to the Legal
Defeasance or the Covenant Defeasance have been complied with.

SECTION 8.05    Deposited Money and Government Securities to be Held in Trust;
                Other Miscellaneous Provisions.

      Subject to Section 8.06 hereof, all money and non-callable Government
Securities (including the proceeds thereof) deposited with the Trustee (or other
qualifying trustee, collectively for purposes of this Section 8.05, the
"Trustee") pursuant to Section 8.04 hereof in respect of the outstanding Notes
shall be held in trust and applied by the Trustee, in accordance with the
provisions of such Notes and this Indenture, to the payment, either directly or
through any Paying Agent (including the Company acting as Paying Agent) as the
Trustee may determine, to the Holders of such Notes of all sums due and to
become due thereon in respect of principal, premium, if any, and interest, but
such money need not be segregated from other funds except to the extent required
by law.

      The Company shall pay and indemnify the Trustee against any tax, fee or
other charge imposed on or assessed against the cash or non-callable Government
Securities deposited pursuant to Section 8.04 hereof or the principal and
interest received in respect thereof other than any such tax, fee or other
charge which by law is for the account of the Holders of the outstanding Notes.

      Anything in this Article 8 to the contrary notwithstanding, the Trustee
shall deliver or pay to the Company from time to time upon the request of the
Company any money or non-callable Government Securities held by it as provided
in Section 8.04 hereof which, in the opinion of a nationally recognized firm of
independent public accountants expressed in a written certification thereof
delivered to the Trustee (which may be the opinion delivered under Section
8.04(a) hereof), are in excess of the amount thereof that would then be required
to be deposited to effect an equivalent Legal Defeasance or Covenant Defeasance.

SECTION 8.06    Repayment to Company.

      Any money deposited with the Trustee or any Paying Agent, or then held by
the Company, in trust for the payment of the principal of, premium, if any, or
interest on any Note and remaining unclaimed for two years after such principal,
and premium, if any, or interest has become due and payable shall be paid to the
Company on its request or (if then held by the Company) shall be discharged from
such trust; and the Holder of such Note shall thereafter look only to the
Company for payment thereof, and all liability of the Trustee or such Paying
Agent with respect to such trust money, and all liability of the Company as
trustee thereof, shall thereupon cease; provided, however, that the Trustee or
such Paying Agent, before being

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required to make any such repayment, may at the expense of the Company cause to
be published once, in the New York Times and The Wall Street Journal (national
edition), notice that such money remains unclaimed and that, after a date
specified therein, which shall not be less than 30 days from the date of such
notification or publication, any unclaimed balance of such money then remaining
will be repaid to the Company.

SECTION 8.07    Reinstatement.

      If the Trustee or Paying Agent is unable to apply any United States
dollars or non-callable Government Securities in accordance with Section 8.02 or
8.03 hereof, as the case may be, by reason of any order or judgment of any court
or governmental authority enjoining, restraining or otherwise prohibiting such
application, then the Company's obligations under this Indenture and the Notes
shall be revived and reinstated as though no deposit had occurred pursuant to
Section 8.02 or 8.03 hereof until such time as the Trustee or Paying Agent is
permitted to apply all such money in accordance with Section 8.02 or 8.03
hereof, as the case may be; provided, however, that, if the Company makes any
payment of principal of, premium, if any, or interest on any Note following the
reinstatement of its obligations, the Company shall be subrogated to the rights
of the Holders of such Notes to receive such payment from the money held by the
Trustee or Paying Agent.

                                    ARTICLE 9

                        AMENDMENT, SUPPLEMENT AND WAIVER

SECTION 9.01    Without Consent of Holders of Notes.

      Notwithstanding Section 9.02 of this Indenture, the Company, the
Guarantors and the Trustee may amend or supplement this Indenture, the
Subsidiary Guarantees or the Notes without the consent of any Holder of a Note:

      (a) to cure any ambiguity, omission, defect or inconsistency;

      (b) to provide for the assumption by a successor company of the
obligations of the Company under this Indenture;

      (c) to provide for uncertificated Notes in addition to or in place of
certificated Notes (provided that the uncertificated Notes are issued in
registered form for purposes of Section 163(f) of the Code, or in a manner such
that the uncertificated Notes are described in Section 163(f)(2)(B) of the
Code);

      (d) to add guarantees with respect to the Notes to secure the Notes;

      (e) to secure the Notes and/or the Subsidiary Guarantees;

      (f) to add to the covenants of the Company for the benefit of the Holders
of the Notes or to surrender any right or power conferred upon the Company;

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      (g) to make any change that does not adversely affect the rights of any
Holder of the Notes as stated in an Opinion of Counsel delivered to the Trustee;
or

      (h) to comply with any requirement of the SEC in connection with the
qualification of this Indenture under the Trust Indenture Act.

      Upon the request of the Company accompanied by a resolution of its Board
of Directors authorizing the execution of any such amended or supplemental
Indenture, and upon receipt by the Trustee of the documents described in Section
7.02 hereof, the Trustee shall join with the Company and the Guarantors in the
execution of any amended or supplemental Indenture authorized or permitted by
the terms of this Indenture and to make any further appropriate agreements and
stipulations that may be therein contained, but the Trustee shall not be
obligated to enter into such amended or supplemental Indenture that affects its
own rights, duties or immunities under this Indenture or otherwise.

SECTION 9.02    With Consent of Holders of Notes.

      Except as provided below in this Section 9.02, the Company and the Trustee
may amend or supplement this Indenture (including Section 3.09, 4.10 and 4.15
hereof), the Subsidiary Guarantees and the Notes with the consent of the Holders
of at least a majority in principal amount of the Notes then outstanding voting
as a single class (including consents obtained in connection with a tender offer
or exchange offer for, or purchase of, the Notes), and, subject to Sections 6.04
and 6.07 hereof, any existing Default or Event of Default (other than a Default
or Event of Default in the payment of the principal of, premium, if any, or
interest on the Notes, except a payment default resulting from an acceleration
that has been rescinded) or compliance with any provision of this Indenture, the
Subsidiary Guarantees or the Notes may be waived with the consent of the Holders
of a majority in principal amount of the then outstanding Notes voting as a
single class (including consents obtained in connection with a tender offer or
exchange offer for, or purchase of, the Notes).

      Upon the request of the Company accompanied by a resolution of its Board
of Directors authorizing the execution of any such amended or supplemental
Indenture, and upon the filing with the Trustee of evidence satisfactory to the
Trustee of the consent of the Holders of Notes as aforesaid, and upon receipt by
the Trustee of the documents described in Section 7.02 hereof, the Trustee shall
join with the Company in the execution of such amended or supplemental Indenture
unless such amended or supplemental Indenture directly affects the Trustee's own
rights, duties or immunities under this Indenture or otherwise, in which case
the Trustee may in its discretion, but shall not be obligated to, enter into
such amended or supplemental Indenture.

      It shall not be necessary for the consent of the Holders of Notes under
this Section 9.02 to approve the particular form of any proposed amendment or
waiver, but it shall be sufficient if such consent approves the substance
thereof.

      After an amendment, supplement or waiver under this Section becomes
effective, the Company shall mail to the Holders of Notes affected thereby a
notice briefly describing the amendment, supplement or waiver. Any failure of
the Company to mail such notice, or any defect therein, shall not, however, in
any way impair or affect the validity of any such amended

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or supplemental Indenture or waiver. Subject to Sections 6.04 and 6.07 hereof,
the Holders of a majority in aggregate principal amount of the Notes then
outstanding voting as a single class may waive compliance in a particular
instance by the Company with any provision of this Indenture or the Notes.
However, without the consent of each Holder affected, an amendment or waiver
under this Section 9.02 may not (with respect to any Notes held by a
non-consenting Holder):

      (a) reduce the amount of Notes whose Holders must consent to an amendment;

      (b) reduce the rate of or extend the time for payment of interest on any
Note;

      (c) reduce the principal of or extend the Stated Maturity of any Note;

      (d) reduce the amount payable upon the redemption of any Note or change
the time at which any Note may be redeemed as described under Section 3.07
hereof;

      (e) make any Note payable in money other than that stated in the Note;

      (f) impair the right of any Holder of the Notes to receive payment of
principal of and interest on such Holder's Notes on or after the due dates
therefor or to institute suit for the enforcement of any payment on or with
respect to such Holder's Notes;

      (g) make any change in the amendment provisions which require each
Holder's consent or in the waiver provisions;

      (h) release any Guarantor from any of its obligations under its Subsidiary
Guarantee or this Indenture, except in accordance with this Indenture;

      (i) make any change in the ranking or priority of any Note that would
adversely affect the Noteholders; or

      (j) make any change in the provisions of this Indenture described under
Section 4.19 hereof that adversely affects the rights of any Noteholder or amend
the terms of the Notes or this Indenture in a way that would result in the loss
of an exemption from any of the Taxes described thereunder or would otherwise
adversely affect any Noteholder for United States or Mexican tax purposes.

SECTION 9.03    Compliance with Trust Indenture Act.

      Every amendment or supplement to this Indenture or the Notes shall be set
forth in a amended or supplemental Indenture that complies with the TIA as then
in effect.

SECTION 9.04    Revocation and Effect of Consents.

      Until an amendment, supplement or waiver becomes effective, a consent to
it by a Holder of a Note is a continuing consent by the Holder of a Note and
every subsequent Holder of a Note or portion of a Note that evidences the same
debt as the consenting Holder's Note, even if notation of the consent is not
made on any Note. However, any such Holder of a Note or

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subsequent Holder of a Note may revoke the consent as to its Note if the Trustee
receives written notice of revocation before the date the waiver, supplement or
amendment becomes effective. An amendment, supplement or waiver becomes
effective in accordance with its terms and thereafter binds every Holder.

SECTION 9.05    Notation on or Exchange of Notes.

      The Trustee may place an appropriate notation about an amendment,
supplement or waiver on any Note thereafter authenticated. The Company in
exchange for all Notes may issue and the Trustee shall, upon receipt of an
Authentication Order, authenticate new Notes that reflect the amendment,
supplement or waiver.

      Failure to make the appropriate notation or issue a new Note shall not
affect the validity and effect of such amendment, supplement or waiver.

SECTION 9.06    Trustee to Sign Amendments, etc.

      The Trustee shall sign any amended or supplemental Indenture authorized
pursuant to this Article Nine if the amendment or supplement does not adversely
affect the rights, duties, liabilities or immunities of the Trustee. The Company
may not sign an amendment or supplemental Indenture until the Board of Directors
approves it. In executing any amended or supplemental indenture, the Trustee
shall be entitled to receive and (subject to Section 7.01 hereof) shall be fully
protected in relying upon, in addition to the documents required by Section
12.04 hereof, an Officers' Certificate and an Opinion of Counsel stating that
the execution of such amended or supplemental indenture is authorized or
permitted by this Indenture.

                                   ARTICLE 10

                              SUBSIDIARY GUARANTEES

SECTION 10.01   Guarantee.

      Subject to this Article 10, each of the Guarantors together with any
future Restricted Subsidiary which in accordance with Section 4.18 hereof is
required in the future to guarantee the Obligations of the Company and the
Guarantors under the Subsidiary Guarantees and this Indenture, upon execution of
a supplemental indenture, hereby, jointly and severally, unconditionally
guarantees to each Holder of a Note authenticated and delivered by the Trustee
and to the Trustee and its successors and assigns, irrespective of the validity
and enforceability of this Indenture, the Notes or the Obligations of the
Company hereunder or thereunder and the Guarantors hereunder, that: (a) the
principal of, premium, if any, any interest, and Additional Amounts, if any, on
the Notes (including, without limitation, any interest that accrues after, or
would accrue but for, the commencement of a proceeding of the type described in
Sections 6.01(i) and (j)) and any fees, expenses and other amounts owing under
this Indenture will be duly and punctually paid in full when due, whether at
Stated Maturity, by acceleration, mandatory redemption, call for redemption,
upon an Asset Sale Offer, Put Offer, purchase or otherwise, and interest on the
overdue principal and (to the extent permitted by law) interest, if any, on the
Notes and any other amounts due in respect of the Notes, and all other
Obligations of the Company and the Guarantors, including the Company's
Obligations to the Holders of the Notes

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under this Indenture and the Notes, and the other Guarantors' Obligations under
their Subsidiary Guarantees, whether now or hereafter existing, will be promptly
paid in full or performed, all strictly in accordance with the terms hereof and
of the Notes; and (ii) in case of any extension of time of payment or renewal of
any Notes or any of such other obligations, the same will be promptly paid in
full when due or performed in accordance with the terms of the extension or
renewal, whether at Stated Maturity, by acceleration, mandatory redemption, call
for redemption, upon Put Offer, Asset Sale Offer, purchase or otherwise. If
payment is not made when due of any amount so guaranteed for whatever reason,
Guarantor shall be jointly and severally obligated to pay the same individually
whether or not such failure to pay has become an Event of Default which could
cause acceleration pursuant to Section 6.02. Each Guarantor agrees that this is
a guarantee of payment and not a guarantee of collection. An Event of Default
under this Indenture or the Notes shall constitute an Event of Default under
each Guarantee, and shall entitle the Holders to accelerate the obligations of
each Guarantor hereunder in the same manner and to the same extent as the
obligations of the Company. Each Subsidiary Guarantee is intended to be superior
to or pari passu in right of payment with all Indebtedness of the respective
Guarantor and each Guarantor's obligations are independent of any obligation of
the Company or any other Guarantor.

      (b) Each Guarantor waives presentation to, demand of, payment from and
protest to the Company of any of the obligations under this Indenture or the
Securities and also waives notice of protest for nonpayment. Each Guarantor
waives notice of any default under the Notes or under this Indenture of the
Notes. The obligations of each Guarantor hereunder shall not be affected by (i)
the failure of any Holder or the Trustee to assert any claim or demand or to
enforce any right or remedy against the Company or any other Person under this
Indenture, the Notes or any other agreement or otherwise; (ii) any extension or
renewal of any thereof; (iii) any rescission, waiver, amendment or modification
of any of the terms or provisions of this Indenture, the Notes or any other
agreement; (iv) the release of any security held by any Holder, or the Trustee
or the Collateral Agent for the obligations or any of them; (v) the failure of
any Holder, or the Trustee, to exercise any right or remedy against any other
guarantor of the obligations of the Company hereunder and under the Notes; or
(vi) any change in the ownership of any such Guarantor.

      (c) The obligations of each Guarantor hereunder shall not be subject to
any reduction, limitation, impairment or termination for any reason, including
any claim of waiver, release, surrender, alteration or compromise, and shall not
be subject to any defense of setoff, counterclaim, recoupment or termination
whatsoever or by reason of the invalidity, illegality or unenforceability of the
obligations of the Company hereunder or under the Notes or otherwise. Without
limiting the generality of the foregoing, the obligations of each Guarantor
herein shall not be discharged or impaired or otherwise affected by the failure
of any Holder or the Trustee to assert any claim or demand or to enforce any
remedy under this Indenture, the Notes or any other agreement, by any waiver or
modification of any thereof, by any default, failure or delay, willful or
otherwise, in the performance of the obligations of the Company hereunder or
under the Notes, or by any other act or thing or omission or delay to do any
other act or thing which may or might in any manner or to any extent vary the
risk of such Guarantor or would otherwise operate as a discharge of such
Guarantor as a matter of law or equity.

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      (d) Each Guarantor further agrees that the Subsidiary Guarantee to which
it is an obligor shall continue to be effective or be reinstated, as the case
may be, if at any time payment, or any part thereof, of principal of, premium,
if any, on or interest (or Additional Amounts, if any) on any obligation of the
Company is rescinded or must otherwise be restored by any Holder or the Trustee
upon the bankruptcy or reorganization of the Company or otherwise.

      (e) In furtherance of the foregoing and not in limitation of any other
right which any Holder or the Trustee has at law or in equity against any
Guarantor by virtue hereof, upon the failure of the Company to pay the principal
of, premium, if any, on or interest (or Additional Amounts, if any) on any of
its obligations hereunder or under the Notes when and as the same shall become
due, whether at maturity, by acceleration, by redemption or otherwise, or to
perform or comply with any other obligation, each Guarantor hereby promises to
and will, upon receipt of written demand by the Trustee, forthwith pay, or cause
to be paid, in cash, to the Holders or the Trustee an amount equal to the sum of
(i) the unpaid amount of such obligations hereunder or under the Notes, (ii)
accrued and unpaid interest on such obligations (but only to the extent not
prohibited by law) and (iii) all other monetary obligations of the Company to
the Holders and the Trustee.

      (f) Until such time as the Notes and the other obligations of the Company
guaranteed hereby have been satisfied in full, each Guarantor hereby irrevocably
waives any claim or other rights that it may now or hereafter acquire against
the Company or any other Guarantor that arise from the existence, payment,
performance or enforcement of such Guarantor's obligations under its Subsidiary
Guarantee, as applicable, including, without limitation, any right of
subrogation, reimbursement, exoneration, contribution or indemnification and any
right to participate in any claim or remedy of the Holders or the Trustee
against the Company or any other Guarantor or any security, whether or not such
claim, remedy or right arises in equity or under contract, statute or common
law, including, without limitation, the right to take or receive from the
Company or any other Guarantor, directly or indirectly, in cash or other
property or by set-off or in any other manner, payment or security on account of
such claim, remedy or right. If any amount shall be paid to such Guarantor in
violation of the preceding sentence at any time prior to the later of the
payments in full of the Notes and all other amounts payable under this
Indenture, and each Subsidiary Guarantee upon the Stated Maturity of the Notes,
such amount shall be held in trust for the benefit of the Holders and the
Trustee and shall forthwith be paid to the Trustee to be credited and applied to
the Notes and all other amounts payable under each Subsidiary Guarantee, whether
matured or unmatured, in accordance with the terms of this Indenture, or to be
held as security for any obligations or other amounts payable under any
Subsidiary Guarantee thereafter arising.

      (g) Each Guarantor acknowledges that it will receive direct and indirect
benefits from the financing arrangements contemplated by this Indenture and that
the waiver set forth in this Section 10.01 is knowingly made in contemplation of
such benefits. Each Guarantor further agrees that, as between it, on the one
hand, and the Holders and the Trustee, on the other hand, (x) subject to this
Article 10, the maturity of the obligations of the Company guaranteed hereby may
be accelerated as provided in Article 6 for the purposes of its Subsidiary
Guarantee, notwithstanding any stay, injunction or other prohibition preventing
such acceleration in respect of the obligations guaranteed hereby, and (y) in
the event of any acceleration of such obligations of the Company guaranteed
hereby as provided in Article 6, such obligations (whether or not due

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and payable) shall further then become due and payable by the Guarantor for the
purposes of each Subsidiary Guarantee.

      (h) A Guarantor that makes a distribution or payment under a Subsidiary
Guarantee shall be entitled to contribution from each other Guarantor in a pro
rata amount based on the Adjusted Net Assets of each such other Guarantor for
all payments, damages and expenses incurred by that Guarantor in discharging the
Company's obligations with respect to the Notes and this Indenture or any other
Guarantor with respect to its Subsidiary Guarantee, so long as the exercise of
such right does not impair the rights of the Holders of the Notes under the
Subsidiary Guarantees.

      (i) Each Guarantor also agrees to pay any and all costs and expenses
(including reasonable attorneys' fees) incurred by the Trustee or any Holder in
enforcing any rights under this Section 10.01.

SECTION 10.02   Limitation on Liability.

      The obligations of each Guarantor will be limited to the maximum amount as
will, after giving effect to all other contingent and fixed liabilities of such
Guarantor and after giving effect to any collections from or payments made by or
on behalf of any other Guarantor in respect of the obligations of such other
Guarantor under its Subsidiary Guarantee, or pursuant to its contribution
obligations under this Indenture, result in the obligations of such Guarantor
under its Subsidiary Guarantee, not constituting a fraudulent conveyance or
fraudulent transfer under Federal or State law or otherwise not being void,
voidable or unenforceable under any bankruptcy, reorganization, receivership,
insolvency, liquidation or other similar legislation or legal principles under
any applicable foreign law. Each Guarantor that makes a payment or distribution
under its Guarantee shall be entitled to a contribution from each other
Guarantor in a pro rata amount based on the Adjusted Net Assets of each
Guarantor.

SECTION 10.03   Limitation on Guarantor Liability.

      Each Guarantor, and by its acceptance of Notes, each Holder, hereby
confirms that it is the intention of all such parties that the Subsidiary
Guarantee of such Guarantor not constitute a fraudulent transfer or conveyance
for purposes of Bankruptcy Law, the Uniform Fraudulent Conveyance Act, the
Uniform Fraudulent Transfer Act or any similar federal or state law to the
extent applicable to any Subsidiary Guarantee. To effectuate the foregoing
intention, the Trustee, the Holders and the Guarantors hereby irrevocably agree
that the obligations of such Guarantor will, after giving effect to such maximum
amount and all other contingent and fixed liabilities of such Guarantor that are
relevant under such laws, and after giving effect to any collections from,
rights to receive contribution from or payments made by or on behalf of any
other Guarantor in respect of the obligations of such other Guarantor under this
Article 10, result in the obligations of such Guarantor under its Subsidiary
Guarantee not constituting a fraudulent transfer or conveyance.

SECTION 10.04   Execution and Delivery of Subsidiary Guarantee.

      To evidence its Subsidiary Guarantee set forth in Section 10.01, each
Guarantor hereby agrees that a notation of such Subsidiary Guarantee
substantially in the form included in Exhibit

                                       82
<PAGE>

B shall be endorsed by an Officer of such Guarantor on each Note authenticated
and delivered by the Trustee and that this Indenture shall be executed on behalf
of such Guarantor by its President or one of its Vice Presidents.

      Each Guarantor hereby agrees that its Subsidiary Guarantee set forth in
Section 10.01 shall remain in full force and effect notwithstanding any failure
to endorse on each Note a notation of such Subsidiary Guarantee.

      If an Officer whose signature is on this Indenture or on the Subsidiary
Guarantee no longer holds that office at the time the Trustee authenticates the
Note on which a Subsidiary Guarantee is endorsed, the Subsidiary Guarantee shall
be valid nevertheless.

      The delivery of any Note by the Trustee, after the authentication thereof
hereunder, shall constitute due delivery of the Subsidiary Guarantee set forth
in this Indenture on behalf of the Guarantors.

      In the event that the Company creates or acquires any new Subsidiaries
subsequent to the date of this Indenture, if required by Section 4.18 hereof,
the Company shall cause such Subsidiaries to execute supplemental indentures to
this Indenture and Subsidiary Guarantees in accordance with Section 4.18 hereof
and this Article 10, to the extent applicable.

SECTION 10.05   No Waiver.

      Neither a failure nor a delay on the part of the Trustee or the Holders in
exercising any right, power or privilege under this Article 10 shall operate as
a waiver thereof, nor shall a single or partial exercise thereof preclude any
other or further exercise of any right, power or privilege. The rights, remedies
and benefits of the Trustee and the Holders herein expressly specified are
cumulative and not exclusive of any other rights, remedies or benefits which
either may have under this Article 10 at law, in equity, by statute or
otherwise.

SECTION 10.06   Modification.

      No modification, amendment or waiver of any provision of this Article 10,
nor the consent to any departure by any Guarantor therefrom, shall in any event
be effective unless the same shall be in writing and signed by the Trustee, and
then such waiver or consent shall be effective only in the specific instance and
for the purpose for which given. No notice to or demand on any Guarantor in any
case shall entitle such Guarantor to any other or further notice or demand in
the same, similar or other circumstances.

SECTION 10.07   Guarantors May Consolidate, etc., on Certain Terms.

      Except as otherwise provided in Section 10.08 hereof, no Guarantor may
consolidate with or merge with or into (whether or not such Guarantor is the
surviving Person) another Person whether or not affiliated with such Guarantor
unless:

      (a) subject to Section 10.08 hereof, the Person formed by or surviving any
such consolidation or merger (if other than a Guarantor or the Company)
unconditionally assumes all the obligations of such Guarantor, pursuant to a
supplemental indenture in form and substance

                                       83
<PAGE>

reasonably satisfactory to the Trustee, under the Notes, the Indenture and the
Subsidiary Guarantee on the terms set forth herein or therein; and

      (b) immediately after giving effect to such transaction, no Default or
Event of Default exists.

      In case of any such consolidation, merger, sale or conveyance and upon the
assumption by the successor Person, by supplemental indenture, executed and
delivered to the Trustee and satisfactory in form to the Trustee, of the
Subsidiary Guarantee endorsed upon the Notes and the due and punctual
performance of all of the covenants and conditions of this Indenture to be
performed by the Guarantor, such successor Person shall succeed to and be
substituted for the Guarantor with the same effect as if it had been named
herein as a Guarantor. Such successor Person thereupon may cause to be signed
any or all of the Subsidiary Guarantees to be endorsed upon all of the Notes
issuable hereunder which theretofore shall not have been signed by the Company
and delivered to the Trustee. All the Subsidiary Guarantees so issued shall in
all respects have the same legal rank and benefit under this Indenture as the
Subsidiary Guarantees theretofore and thereafter issued in accordance with the
terms of this Indenture as though all of such Subsidiary Guarantees had been
issued at the date of the execution hereof.

      Except as set forth in Articles 4 and 5 hereof, and notwithstanding
clauses (a) and (b) above, nothing contained in this Indenture or in any of the
Notes shall prevent any consolidation or merger of a Guarantor with or into the
Company or another Guarantor, or shall prevent any sale or conveyance of the
property of a Guarantor as an entirety or substantially as an entirety to the
Company or another Guarantor.

SECTION 10.08   Releases Following Sale of Assets.

      In the event of a sale or other disposition of all of the assets of any
Guarantor, by way of merger, consolidation or otherwise, or a sale or other
disposition of all the capital stock of any Guarantor, in each case to a Person
that is not the Company (either before or after giving effect to such
transactions) or a Restricted Subsidiary of the Company, then such Guarantor (in
the event of a sale or other disposition, by way of merger, consolidation or
otherwise, of all of the capital stock of such Guarantor) or the corporation
acquiring the property (in the event of a sale or other disposition of all or
substantially all of the assets of such Guarantor) will be released and relieved
of any obligations under its Subsidiary Guarantee; provided that the net
proceeds of such sale or other disposition are applied in accordance with the
applicable provisions of this Indenture, including without limitation Section
4.10 hereof. Upon delivery by the Company to the Trustee of an Officers'
Certificate and an Opinion of Counsel to the effect that such sale or other
disposition was made by the Company in accordance with the provisions of this
Indenture, including without limitation Section 4.10 hereof, the Trustee shall
execute any documents reasonably required in order to evidence the release of
any Guarantor from its obligations under its Subsidiary Guarantee.

      Any Guarantor not released from its obligations under its Subsidiary
Guarantee shall remain liable for the full amount of principal of and interest
on the Notes and for the other obligations of any Guarantor under this Indenture
as provided in this Article 10.

                                       84
<PAGE>

                                   ARTICLE 11

                           SATISFACTION AND DISCHARGE

SECTION 11.01   Satisfaction and Discharge.

      This Indenture will be discharged and will cease to be of further effect
as to all Notes issued hereunder, when:

      (1) either:

            (a)   all Notes that have been authenticated (except lost, stolen or
                  destroyed Notes that have been replaced or paid and Notes for
                  whose payment money has theretofore been deposited in trust
                  and thereafter repaid to the Company) have been delivered to
                  the Trustee for cancellation; or

            (b)   all Notes that have not been delivered to the Trustee for
                  cancellation have become due and payable by reason of the
                  making of a notice of redemption or otherwise or will become
                  due and payable within one year and the Company or any
                  Guarantor has irrevocably deposited or caused to be deposited
                  with the Trustee as trust funds in trust solely for the
                  benefit of the Holders, cash in U.S. dollars, non-callable
                  Government Securities, or a combination thereof, in such
                  amounts as will be sufficient without consideration of any
                  reinvestment of interest, to pay and discharge the entire
                  indebtedness on the Notes not delivered to the Trustee for
                  cancellation for principal, premium and Additional Interest,
                  if any, and accrued interest to the date of maturity or
                  redemption;

      (2)   no Default or Event of Default shall have occurred and be continuing
            on the date of such deposit or shall occur as a result of such
            deposit and such deposit will not result in a breach or violation
            of, or constitute a default under, any other instrument to which the
            Company or any Guarantor is a party or by which the Company or any
            Guarantor is bound;

      (3)   the Company or any Guarantor has paid or caused to be paid all sums
            payable by it under this Indenture; and

      (4)   the Company has delivered irrevocable instructions to the Trustee
            under this Indenture to apply the deposited money toward the payment
            of the Notes at maturity or the redemption date, as the case may be.

In addition, the Company must deliver an Officers' Certificate and an Opinion of
Counsel to the Trustee stating that all conditions precedent to satisfaction and
discharge have been satisfied.

      Notwithstanding the satisfaction and discharge of this Indenture, if money
shall have been deposited with the Trustee pursuant to subclause (b) of clause
(1) of this Section, the provisions of Section 11.02 and Section 8.06 shall
survive.

                                       85
<PAGE>

SECTION 11.02   Application of Trust Money.

      Subject to the provisions of Section 8.06, all money deposited with the
Trustee pursuant to Section 11.01 shall be held in trust and applied by it, in
accordance with the provisions of the Notes and this Indenture, to the payment,
either directly or through any Paying Agent (including the Company acting as its
own Paying Agent) as the Trustee may determine, to the Persons entitled thereto,
of the principal (and premium, if any) and interest for whose payment such money
has been deposited with the Trustee; but such money need not be segregated from
other funds except to the extent required by law.

      If the Trustee or Paying Agent is unable to apply any money or Government
Securities in accordance with Section 11.01 by reason of any legal proceeding or
by reason of any order or judgment of any court or governmental authority
enjoining, restraining or otherwise prohibiting such application, the Company's
and any Guarantor's obligations under this Indenture and the Notes shall be
revived and reinstated as though no deposit had occurred pursuant to Section
11.01; provided that if the Company has made any payment of principal of,
premium, if any, or interest on any Notes because of the reinstatement of its
obligations, the Company shall be subrogated to the rights of the Holders of
such Notes to receive such payment from the money or Government Securities held
by the Trustee or Paying Agent.

                                   ARTICLE 12

                                  MISCELLANEOUS

SECTION 12.01   Trust Indenture Act Controls.

      If any provision of this Indenture limits, qualifies or conflicts with the
duties imposed by TIA Section 318(c), the imposed duties shall control.

SECTION 12.02   Notices.

      Any notice or communication by the Company, any Guarantor or the Trustee
to the others is duly given if in English and in writing and delivered in Person
or mailed by first class mail (registered or certified, return receipt
requested), telex, telecopier or overnight air courier guaranteeing next day
delivery, to the others' address:

      If to the Company and/or any Guarantor:

      Maxcom Telecomunicaciones, S.A. de C.V.
      Guillermo Gonzalez Camarena #2000
      Col. Centro De Ciudad Santa Fe
      01210 Mexico D.F.
      Telecopier No.:  +(5255) 5147-1310
      Attention:  Legal Department

                                       86
<PAGE>

      With a copy to:
      Kirkland & Ellis LLP
      200 East Randolph Drive
      Chicago, Illinois   60601
      Telecopier No.:  (312) 861-2200
      Attention: Margaret A. Gibson, P.C.
                 and Michael D. Belsley, Esq.

      If to the Trustee:
      The Bank of New York
      101 Barclay Street, Floor 21W
      New York, New York  10286
      Telecopier No.:  (212) 815-5203
      Attention:  Corporate Trust Administration - Global Finance Unit

      The Company, any Guarantor or the Trustee, by notice to the others may
designate additional or different addresses for subsequent notices or
communications.

      All notices and communications (other than those sent to Holders) shall be
given in English and shall be deemed to have been duly given when actually
received.

      Any notice or communication to a Holder shall be mailed by first class
mail, certified or registered, return receipt requested, or by overnight air
courier guaranteeing next day delivery to its address shown on the register kept
by the Registrar. Any notice or communication shall also be so mailed to any
Person described in TIA Section 313(c), to the extent required by the TIA.
Failure to mail a notice or communication to a Holder or any defect in it shall
not affect its sufficiency with respect to other Holders.

      If a notice or communication is mailed in the manner provided above within
the time prescribed, it is duly given, whether or not the addressee receives it.

      If the Company mails a notice or communication to Holders, it shall mail a
copy to the Trustee and each Agent at the same time.

SECTION 12.03   Communication by Holders of Notes with Other Holders of Notes.

      Holders may communicate pursuant to TIA Section 312(b) with other Holders
with respect to their rights under this Indenture or the Notes. The Company, the
Trustee, the Registrar and anyone else shall have the protection of TIA Section
312(c).

SECTION 12.04   Certificate and Opinion as to Conditions Precedent.

      Upon any request or application by the Company to the Trustee to take any
action under this Indenture, the Company shall furnish to the Trustee:

      (a) an Officers' Certificate in form and substance reasonably satisfactory
to the Trustee (which shall include the statements set forth in Section 12.06
hereof) stating that, in the opinion

                                       87
<PAGE>

of the signers, all conditions precedent and covenants, if any, provided for in
this Indenture relating to the proposed action have been satisfied; and

      (b) an Opinion of Counsel in form and substance reasonably satisfactory to
the Trustee (which shall include the statements set forth in Section 12.06
hereof) stating that, in the opinion of such counsel, all such conditions
precedent and covenants have been satisfied.

SECTION 12.05   Form of Documents Delivered to a Trustee.

      In any case where several matters are required to be certified by, or
covered by an opinion of, any specified Person, it is not necessary that all
such matters be certified by, or covered by the opinion of, only one such
Person, or that they be so certified or covered by only one document, but one
such Person may certify or give an opinion with respect to some matters and one
or more other such Persons as to other matters, and any such Person may certify
or give an opinion as to such matters in one or several documents.

      Any certificate or opinion of an officer of the Company may be based,
insofar as it relates to legal matters, upon a certificate or opinion of, or
representations by, counsel, unless such officer knows, or in the exercise of
reasonable care should know, that the certificate or opinion or representations
with respect to the matters upon which his certificate or opinion is based are
erroneous. Any such certificate or opinion of counsel may be based, insofar as
it relates to factual matters, upon a certificate or opinion of, or
representations by, an officer or officers of the Company stating that the
information with respect to such factual matters is in the possession of the
Company, unless such counsel knows, or in the exercise of reasonable care should
know, that the certificate or opinion or representations with respect to such
matters are erroneous.

      Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Indenture, they may, but need not, be consolidated and
form one instrument.

SECTION 12.06   Statements Required in Certificate or Opinion.

      Each certificate or opinion with respect to compliance with a condition or
covenant provided for in this Indenture (other than a certificate provided
pursuant to TIA Section 314(a)(4)) shall comply with the provisions of TIA
Section 314(e) and shall include:

      (a) a statement that the Person making such certificate or opinion has
read such covenant or condition;

      (b) a brief statement as to the nature and scope of the examination or
investigation upon which the statements or opinions contained in such
certificate or opinion are based;

      (c) a statement that, in the opinion of such Person, he or she has made
such examination or investigation as is necessary to enable him to express an
informed opinion as to whether or not such covenant or condition has been
satisfied; and

      (d) a statement as to whether or not, in the opinion of such Person, such
condition or covenant has been satisfied.

                                       88
<PAGE>

SECTION 12.07   Rules by Trustee and Agents.

      The Trustee may make reasonable rules for action by or at a meeting of
Holders. The Registrar or Paying Agent may make reasonable rules and set
reasonable requirements for its functions.

SECTION 12.08   No Personal Liability of Directors, Officers, Employees and
                Stockholders.

      No past, present or future director, officer, employee, incorporator or
stockholder of the Company or any Guarantor, as such, shall have any liability
for any obligations of the Company or such Guarantor under the Notes, the
Subsidiary Guarantees or this Indenture or for any claim based on, in respect
of, or by reason of, such obligations or their creation. Each Holder by
accepting a Note waives and releases all such liability. The waiver and release
are part of the consideration for issuance of the Notes.

SECTION 12.09   Governing Law, Submission to Jurisdiction and Waiver of Jury
                Trial.

      This Indenture and all of the rights and obligations of the parties hereto
shall be governed by and construed in accordance with the laws of the State of
New York without giving effect to the conflict of law provisions thereof, and if
any dispute or controversy related to or arising out of this Indenture is
brought before a Mexican court, the parties hereto agree that this Indenture
shall be governed by and construed in accordance with the laws of the State of
New York without giving effect to the conflict of law provisions thereof.

      Any action or proceeding relating in any way to this Indenture may be
brought and enforced in the federal courts of the United States for the Southern
District of New York, and each of the parties hereto irrevocably submits to the
nonexclusive jurisdiction of each such court in respect of any such action or
proceeding and the Company and the Guarantor hereby expressly waive any
jurisdiction rights they may be entitled to by reason of their present or future
domicile or otherwise; provided, that if for whatever reason the federal courts
of the United States for the Southern District of New York will not or cannot
hear such action or proceeding, it may be brought and enforced in the courts of
the State of New York in The City of New York, Borough of Manhattan. Each of the
Company and each of the Guarantor irrevocably appoints CT Corporation System,
with offices at 111 Eighth Avenue, 13th Floor, New York, New York 10011, as its
agent to receive service of process or other legal summons for purposes of any
such action or proceeding. So long as the Company or the Guarantor has any
obligation under this Indenture, it will maintain a duly appointed agent in The
City of New York, Borough of Manhattan for the service of such process or
summons, and if it fails to maintain such an agent, any such process or summons
may be served by mailing a copy thereof by registered mail, or a form of mail
substantially equivalent thereto, addressed to it at its address as provided for
notices hereunder.

      Each of the Company and the Guarantor irrevocably waives, to the fullest
extent permitted by applicable law, all immunity (whether on the basis of
sovereignty or otherwise) from jurisdiction, attachment (both before and after
judgment) and execution to which it might otherwise be entitled in any action or
proceeding relating in any way to this Indenture in the courts of Mexico or the
United States, of the State of New York or of any other country or

                                       89
<PAGE>

jurisdiction, and the Company and the Guarantor shall not raise a claim or cause
to be pleaded any such immunity at or in respect of any such action or
proceeding.

      Each of the parties irrevocable waives, to the fullest extent permitted by
applicable law, any objection that it may now or hereafter have to the laying of
venue of any such action or proceeding in the United States District Court for
the Southern District of New York, or the Supreme Court of the State of New
York, County of New York and any claim that any such action or proceeding
brought in any such court has been brought in an inconvenient forum.

      EACH OF THE COMPANY, THE GUARANTORS AND THE TRUSTEE HEREBY IRREVOCABLY
WAIVES, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY AND ALL RIGHT TO
TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS
INDENTURE, THE NOTES OR THE TRANSACTIONS CONTEMPLATED HEREBY.

SECTION 12.10   No Adverse Interpretation of Other Agreements.

      This Indenture may not be used to interpret any other indenture, loan or
debt agreement of the Company or its Subsidiaries or of any other Person. Any
such indenture, loan or debt agreement may not be used to interpret this
Indenture.

SECTION 12.11   Successors.

      All agreements of the Company in this Indenture and the Notes shall bind
its successors. All agreements of the Trustee in this Indenture shall bind its
successors. All agreements of each Guarantor in this Indenture shall bind its
successors, except as otherwise provided in Section 10.08.

SECTION 12.12   Severability.

      In case any provision in this Indenture or in the Notes shall be invalid,
illegal or unenforceable, the validity, legality and enforceability of the
remaining provisions shall not in any way be affected or impaired thereby.

SECTION 12.13   Counterpart Originals.

      The parties may sign any number of copies of this Indenture. Each signed
copy shall be an original, but all of them together represent the same
agreement.

SECTION 12.14   Table of Contents, Headings, etc.

      The Table of Contents, Cross-Reference Table and Headings of the Articles
and Sections of this Indenture have been inserted for convenience of reference
only, are not to be considered a part of this Indenture and shall in no way
modify or restrict any of the terms or provisions hereof.

                         [Signatures on following page]

                                       90
<PAGE>

                                   SIGNATURES

Dated as of October 8, 2004

                                 MAXCOM TELECOMUNICACIONES, S.A. DE C.V.

                                 By: /s/ Jose Antonio Solbes
                                     --------------------------------
                                     Name:  Jose Antonio Solbes
                                     Title: Chief Financial Officer

Attest:

/s/ Gonzalo Alarcon
----------------------
Name:  Gonzalo Alarcon
Title: General Counsel

                                 CORPORATIVO EN TELECOMUNICACIONES, S.A. DE C.V.

                                 By: /s/ Jose Antonio Solbes
                                     ------------------------------------------
                                     Name:  Jose Antonio Solbes
                                     Title: Chief Financial Officer

Attest:

/s/ Gonzalo Alarcon
--------------------------
Name:  Gonzalo Alarcon
Title: General Counsel

                                 MAXCOM SERVICIOS ADMINISTRATIVOS, S.A. DE C.V.

                                 By: /s/ Jose Antonio Solbes
                                     ----------------------------------
                                     Name:  Jose Antonio Solbes
                                     Title: Chief Financial Officer

Attest:

/s/ Gonzalo Alarcon
------------------------
Name:  Gonzalo Alarcon
Title: General Counsel

                                       91
<PAGE>

                                           MAXCOM USA, INC.

                                           By: /s/ Jose Antonio Solbes
                                               -------------------------------
                                               Name:  Jose Antonio Solbes
                                               Title: Chief Financial Officer

Attest:

/s/ Gonzalo Alarcon
--------------------------
Name:  Gonzalo Alarcon
Title: General Counsel

                                          THE BANK OF NEW YORK

                                          By: /s/ Ritu Khanna
                                              -------------------------------
                                              Name:  Ritu Khanna
                                              Title: Assistant Vice President

                                       92
<PAGE>

                                                                       EXHIBIT A

                                 [Face of Note]

[Insert the Global Note Legend or Original Issue Discount Legend, if applicable
pursuant to the provisions of the Indenture]

                                                                        CUSIP___

                          Senior Step-Up Notes due 2009

No.__                                                                   U.S.$___

                     MAXCOM TELECOMUNICACIONES, S.A. DE C.V.

promises to pay to _____________________________________________________________

or registered assigns, _________________________________________________________

the principal sum of ___________________________________________________________

Dollars on October 15, 2009.

Interest Payment Dates: April 15, 2005, October 15, 2005, April 15, 2006,
October 15, 2006, April 15, 2007, October 15, 2007, April 15, 2008, October 15,
2008, April 15, 2009 and October 15, 2009.

Record Dates: April 1, 2005, October 1, 2005, April 1, 2006, October 1, 2006,
April 1, 2007, October 1, 2007, April 1, 2008, October 1, 2008, April 1, 2009
and October 1, 2009.

Execution Place: New York, New York

                                       A-1
<PAGE>

Dated as of    , 2004

                                         MAXCOM TELECOMUNICACIONES, S.A. DE C.V.

                                         By: ________________________________
                                             Name:
                                             Title:

This is one of the Notes referred to
in the within-mentioned Indenture:

THE BANK OF NEW YORK,
  as Trustee

By: __________________________
     Authorized Signatory

                                       A-2
<PAGE>

                                 [Back of Note]
                          Senior Step-Up Notes due 2009

      Capitalized terms used herein shall have the meanings assigned to them in
the Indenture referred to below unless otherwise indicated.

      1. INTEREST. Maxcom Telecomunicaciones, S.A. de C.V., a sociedad anonima
de capital variable organized under the laws of Mexico (the "Company"), promises
to pay interest on the principal amount of this Note as follows: (a) if this
Note has not been accelerated as a result of an Event of Default, interest shall
accrue and be payable at a rate of (i) 4.00% for the period commencing on the
Issue Date through and including April 14, 2005, (ii) 5.75% for the period
commencing on April 15, 2005 through and including October 14, 2005, (iii) 7.75%
for the period commencing on October 15, 2005 through and including April 14,
2006, (iv) 8.25% for the period commencing on April 15, 2006 through and
including October 14, 2006, (v) 9.25% for the period commencing on October 15,
2006 through and including October 14, 2007, (vi) 10.25% for the period
commencing on October 15, 2007 through and including October 14, 2008 and (vii)
11.25% for the period commencing on October 15, 2008 through and including
October 14, 2009; (b) if no Event of Default has occurred and is continuing, the
Company will pay such interest and Additional Amounts, if any, semi-annually in
arrears on April 15th and October 15th of each calendar year to the registered
Holder on the Record Date, or if any such Interest Payment Date is not a
Business Day, on the next succeeding Business Day; provided, however, that no
interest payment shall be due hereunder until April 15, 2005; and (c) if an
Event of Default has occurred and is continuing and the then outstanding
principal amount of this Note becomes due and payable pursuant to Section 6.02
of the Indenture as a result of such Event of Default, interest (including
post-petition interest in any proceeding under any Bankruptcy Law) will accrue
at a defaulted interest rate equal to 1.25% per annum in excess of the then
applicable interest rate on the Notes to the extent lawful, on principal and
premium, if any, from the date of occurrence of the Event of Default until this
Note, together with all interest, defaulted interest and Additional Amounts, if
any, is paid in full, and the Company shall pay interest (including
post-petition interest in any proceeding under any Bankruptcy Law) on
installments of interest (without regard to any applicable grace periods) from
time to time on demand at the same rate to the extent lawful. Interest will be
computed on the basis of a 360-day year of twelve 30-day months.

      2. METHOD OF PAYMENT. The Company will pay interest on the Notes (except
defaulted interest) and Additional Amounts, if any, to the Persons who are
registered Holders of Notes at the close of business on the 1st day of the month
in which the Interest Payment Date occurs, even if such Notes are canceled after
such record date and on or before such Interest Payment Date (whether or not a
Business Day), except as provided in Section 2.12 of the Indenture with respect
to defaulted interest. The Notes will be payable as to principal, premium, if
any, and interest and Additional Amounts at the office or agency of the Company
maintained for such purpose within the City and State of New York, or, at the
option of the Company, payment of interest may be made by check mailed from such
office or agency to the Holders at their addresses set forth in the register of
Holders, and provided that payment by wire transfer of immediately available
funds will be required with respect to principal of and interest, premium

                                       A-3
<PAGE>

on, the Global Note and all other Notes the Holders of which shall have provided
wire transfer instructions to the Company or the Paying Agent. Such payment
shall be in such coin or currency of the United States of America as at the time
of payment is legal tender for payment of public and private debts.

      3. PAYING AGENT AND REGISTRAR. Initially, The Bank of New York, the
Trustee under the Indenture, will act as Paying Agent and Registrar. The Company
may change any Paying Agent or Registrar without notice to any Holder. The
Company or any of its Subsidiaries may act in any such capacity.

      4. INDENTURE. The Company issued the Notes under an Indenture, dated as of
October 8, 2004 ("Indenture"), among the Company, Corporativo en
Telecomunicaciones, S.A. de C.V., Maxcom Servicios Administrativos, S.A. de
C.V., Maxcom USA, Inc., and the Trustee. The terms of the Notes include those
stated in the Indenture and those made part of the Indenture by reference to the
Trust Indenture Act of 1939, as amended (15 U.S. Code Sections 77aaa-77bbbb).
The Notes are subject to all such terms, and Holders are referred to the
Indenture and such Act for a statement of such terms. To the extent any
provision of this Note conflicts with the express provisions of the Indenture,
the provisions of the indenture shall govern and be controlling. The Notes are
obligations of the Company limited to U.S.$167,623,590 in aggregate principal
amount, except as provided in Section 2.07 of the Indenture.

      5.  OPTIONAL REDEMPTION.

          (a) The Company may at its option on one or more occasions redeem
Notes in whole or in part at a redemption price (expressed as a percentage of
principal amount) of 101.00%, plus accrued and unpaid interest to the redemption
date

          (b) Without the consent of any Holder, outstanding Notes may be
redeemed at the Company's option at any time in whole, but not in part, upon its
giving irrevocable prior written notice pursuant to Section 3.03 of the
Indenture, if, as a result of any amendment to, or change in, the laws (or any
related regulation or rulings) of Mexico or any related political subdivision or
taxing authority affecting taxation or any amendment to or change in an official
interpretation, administration or application of such laws, regulations or
rulings (including a holding by a court of competent jurisdiction), which
amendment or change of such laws, regulations or rulings becomes effective on or
after the date on which the Notes are originally issued, the Company would or
would become obligated, after taking reasonable measures available to the
Company to avoid such requirement, to pay Excessive Additional Amounts, at a
cash price equal to the sum of:

            (i) 100% of the principal amount of the Note on the date of
      redemption;

            (ii) the related accrued and unpaid interest, if any, to the date of
      redemption; and

            (iii) any Additional Amounts which would otherwise be payable.

                                       A-4
<PAGE>

      Notwithstanding the above no such notice of redemption may be given
earlier than 60 days prior to the earliest date on which, but for such
redemption, the Company would be obligated to pay Excessive Additional Amounts
were any payment on the Notes then due.

      Prior to publication of any notice of redemption pursuant to this Section,
the Company will deliver to the Trustee (1) an Officer's Certificate stating
that the Company is entitled to effect such redemption and setting forth a
statement of facts showing that the conditions precedent to its right to so
redeem the Notes have occurred and (2) a written opinion of independent counsel
in Mexico reasonably acceptable to the Trustee to the effect that the Company
has or will become obligated to pay such Excessive Additional Amounts as a
result of such change or amendment. Once the Company delivers such notice to the
Trustee, it will be irrevocable.

      6.    MANDATORY REDEMPTION.

      Except as set forth in paragraph 7 below, the Company shall not be
required to make mandatory redemption payments with respect to the Notes.

      7.    REPURCHASE AT OPTION OF HOLDER.

            (a) If there is a Put Offer Event, the Company shall be required to
make an offer (a "Put Offer") to repurchase all or any part (equal to U.S.$1.00
or an integral multiple thereof) of each Holder's Notes at a purchase price
equal to 100% of the aggregate principal amount thereof plus accrued and unpaid
interest, to the date of purchase (the "Put Payment"). Within 30 days following
any Put Offer Event, the Company shall mail a notice to each Holder setting
forth the procedures governing the Put Offer as required by the Indenture.
Holders of Notes that are the subject of an offer to purchase will receive a Put
Offer from the Company prior to any related purchase date and may elect to have
such Notes purchased by completing the form entitled "Option of Holder to Elect
Purchase" on the reverse of the Notes.

            (b) If the Company or a Subsidiary consummates any Asset Disposition
and the aggregate amount of Net Available Cash exceeds U.S.$5.0 million, the
Company may commence an offer to all Holders of Notes (an "Asset Sale Offer")
pursuant to Section 3.09 of the Indenture to purchase the maximum principal
amount of Notes that may be purchased out of the Net Available Cash at an offer
price in cash in an amount equal to 100% of the principal amount thereof plus
accrued and unpaid interest and Additional Interest thereon, if any, to the date
fixed for the closing of such offer, in accordance with the procedures set forth
in the Indenture. To the extent that the aggregate amount of Notes tendered
pursuant to an Asset Sale Offer is less than the Net Available Cash, the Company
(or such Subsidiary) may use such deficiency for purposes not prohibited by the
Indenture. If the aggregate principal amount of Notes surrendered by Holders
thereof exceeds the amount of Net Available Cash, the Trustee shall select the
Notes to be purchased on a pro rata basis. Holders of Notes that are the subject
of an offer to purchase will receive an Asset Sale Offer from the Company prior
to any related purchase date and may elect to have such Notes purchased by
completing the form entitled "Option of Holder to Elect Purchase" on the reverse
of the Notes.

                                      A-5
<PAGE>

      8. NOTICE OF REDEMPTION. Notice of redemption will be mailed at least 30
days but not more than 60 days before the redemption date to each Holder whose
Notes are to be redeemed at its registered address. Notes in denominations
larger than U.S.$1.00 may be redeemed in part but only in whole multiples of
U.S.$1.00, unless all of the Notes held by a Holder are to be redeemed. On and
after the redemption date interest ceases to accrue on Notes or portions thereof
called for redemption.

      9. DENOMINATIONS, TRANSFER, EXCHANGE. The Notes are in registered form
without coupons in denominations of U.S.$1.00 and integral multiples of
U.S.$1.00. The transfer of Notes may be registered and Notes may be exchanged as
provided in the Indenture. The Registrar and the Trustee may require a Holder,
among other things, to furnish appropriate endorsements and transfer documents
and the Company may require a Holder to pay any taxes and fees required by law
or permitted by the Indenture. The Company need not exchange or register the
transfer of any Note or portion of a Note selected for redemption, except for
the unredeemed portion of any Note being redeemed in part. Also, the Company
need not exchange or register the transfer of any Notes for a period of 15 days
before a selection of Notes to be redeemed or during the period between a record
date and the corresponding Interest Payment Date.

      10. PERSONS DEEMED OWNERS. The registered Holder of a Note may be treated
as its owner for all purposes.

      11. AMENDMENT, SUPPLEMENT AND WAIVER. Subject to certain exceptions, the
Indenture, the Subsidiary Guarantees or the Notes may be amended or supplemented
with the consent of the Holders of at least a majority in principal amount of
the then outstanding Notes voting as a single class, and any existing default or
compliance with any provision of the Indenture, the Subsidiary Guarantees or the
Notes may be waived with the consent of the Holders of a majority in principal
amount of the then outstanding Notes voting as a single class. Without the
consent of any Holder of a Note, the Indenture, the Subsidiary Guarantees or the
Notes may be amended or supplemented to cure any ambiguity, omission, defect or
inconsistency, to provide for the assumption by a successor company of the
obligations of the Company under this Indenture, to provide for uncertificated
Notes in addition to or in place of certificated Notes (provided that the
uncertificated Notes are issued in registered form for purposes of Section
163(f) of the Code, or in a manner such that the uncertificated Notes are
described in Section 163(f)(2)(B) of the Code), to add guarantees with respect
to the Notes to secure the Notes, to add to the covenants of the Company for the
benefit of the Holders of the Notes or to surrender any right or power conferred
upon the Company, to make any change that does not adversely affect the rights
of any Holder of the Notes, or to comply with any requirement of the SEC in
connection with the qualification of this Indenture under the Trust Indenture
Act.

      12. DEFAULTS AND REMEDIES. Events of Default include in summary form: (i)
default for 30 days in the payment when due of interest, Additional Amounts on
the Notes; (ii) default in payment when due of principal of or premium, if any,
on the Notes including upon redemption offers to purchase or otherwise; (iii)
the Company fails to comply with any of the provisions of Section 5.01 of the
Indenture; (iv) the Company fails to comply with the provisions of clause (c) of
Section 4.04 of the Indenture for a period of 30 or more days commencing on the
date of such

                                      A-6
<PAGE>

default; (v) the Company fails to comply with any of the provisions of Sections
4.07, 4.08, 4.09, 4.10 (other than a failure to purchase Notes), 4.03, 4.11,
4.12, 4.13, 4.15 (other than a failure to purchase Notes), 4.17, or 4.18 of the
Indenture for 30 days after notice to the Company by the Trustee or the Holders
of at least 25% in aggregate principal amount of the Notes then outstanding
voting as a single class; (vi) the Company fails to observe or perform any other
covenant, representation, warranty or other agreement in the Indenture or the
Notes for 60 days after notice to the Company by the Trustee or the Holders of
at least 25% in aggregate principal amount of the Notes then outstanding voting
as a single class; (vii) a default occurs under any mortgage, indenture or
instrument under which there may be issued or by which there may be secured or
evidenced any Indebtedness for money borrowed by the Company or any of its
Significant Subsidiaries, whether such Indebtedness or guarantee now exists, or
is created after the date of this Indenture, which default results in the
acceleration of such Indebtedness prior to its express maturity and, in each
case, the principal amount of such Indebtedness is U.S.$5.0 million or more;
(viii) certain final judgments or decrees for the payment of money that remain
undischarged for 60 consecutive days provided that such undischarged judgments
or decrees exceed U.S.$5.0 million; (ix) certain events of bankruptcy or
insolvency with respect to the Company or any of its Significant Subsidiaries;
and (x) except as permitted by the Indenture, any Subsidiary Guarantee being
held in any final judicial proceeding to be unenforceable or invalid or ceasing
for any reason to be in full force and effect or any Guarantor, or any Person
acting on behalf of any Guarantor, denying or disaffirming its obligations under
such Guarantor's Subsidiary Guarantee. If any Event of Default occurs and is
continuing, the Trustee or the Holders of at least 25% in principal amount of
the then outstanding Notes may declare all the Notes to be due and payable.
Notwithstanding the foregoing, in the case of an Event of Default arising from
certain events of bankruptcy or insolvency, all outstanding Notes will become
due and payable without further action or notice. Holders may not enforce the
Indenture or the Notes except as provided in the Indenture. Subject to certain
limitations, Holders of a majority in principal amount of the then outstanding
Notes may direct the Trustee in its exercise of any trust or power. The Trustee
may withhold from Holders of the Notes notice of any continuing Default or Event
of Default (except a Default or Event of Default relating to the payment of
principal or interest) if it determines that withholding notice is in their
interest. The Holders of a majority in aggregate principal amount of the Notes
then outstanding by notice to the Trustee may on behalf of the Holders of all of
the Notes waive any existing Default or Event of Default and its consequences
under the Indenture except a continuing Default or Event of Default in the
payment of interest on, or the principal of, the Notes. The Company is required
to deliver to the Trustee annually a statement regarding compliance with the
Indenture, and the Company is required upon becoming aware of any Default or
Event of Default, to deliver to the Trustee a statement specifying such Default
or Event of Default.

      13. TRUSTEE DEALINGS WITH COMPANY. The Trustee, in its individual or any
other capacity, may make loans to, accept deposits from, and perform services
for the Company or its Affiliates, and may otherwise deal with the Company or
its Affiliates, as if it were not the Trustee.

      14. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator or stockholder of the Company or any Guarantor,
as such, shall have any liability for any obligations of the Company or such
Guarantor under the Notes, the Subsidiary Guarantees or the Indenture or for any
claim based on, in respect of, or by reason of, such

                                      A-7
<PAGE>

obligations or their creation. Each Holder by accepting a Note waives and
releases all such liability. The waiver and release are part of the
consideration for the issuance of the Notes.

      15. AUTHENTICATION. This Note shall not be valid until authenticated by
the manual signature of the Trustee or an authenticating agent.

      16. ABBREVIATIONS. Customary abbreviations may be used in the name of a
Holder or an assignee, such as: TEN COM (= tenants in common), TEN ENT (=
tenants by the entireties), JT TEN (= joint tenants with right of survivorship
and not as tenants in common), CUST (= Custodian), and U/G/M/A (= Uniform Gifts
to Minors Act).

      17. CUSIP NUMBERS. Pursuant to a recommendation promulgated by the
Committee on Uniform Security Identification Procedures, the Company has caused
CUSIP numbers to be printed on the Notes and the Trustee may use CUSIP numbers
in notices of redemption as a convenience to Holders. No representation is made
as to the accuracy of such numbers either as printed on the Notes or as
contained in any notice of redemption and reliance may be placed only on the
other identification numbers placed thereon.

      18. GOVERNING LAW AND SUBMISSION TO JURISDICTION. This Note and all of the
rights and obligations of the parties hereto shall be governed by and construed
in accordance with the laws of the State of New York without giving effect to
the conflict of law provisions thereof, and if any dispute or controversy
related to or arising out of this Note is brought before a Mexican court, the
parties hereto agree that this Note shall be governed by and construed in
accordance with the laws of the State of New York without giving effect to the
conflict of law provisions thereof.

      Any action or proceeding relating in any way to this Note may be brought
and enforced in the federal courts of the United States for the Southern
District of New York, and each of the parties hereto irrevocably submits to the
nonexclusive jurisdiction of each such court in respect of any such action or
proceeding and the Company and the Guarantor hereby expressly waive any
jurisdiction rights they may be entitled to by reason of their present or future
domicile or otherwise; provided, that if for whatever reason the federal courts
of the United States for the Southern District of New York will not or cannot
hear such action or proceeding, it may be brought and enforced in the courts of
the State of New York in The City of New York, Borough of Manhattan. Each of the
Company and each of the Guarantor irrevocably appoints CT Corporation System,
with offices at 111 Eighth Avenue, 13th Floor, New York, New York 10011, as its
agent to receive service of process or other legal summons for purposes of any
such action or proceeding. So long as the Company or the Guarantor has any
obligation under this Note, it will maintain a duly appointed agent in The City
of New York, Borough of Manhattan for the service of such process or summons,
and if it fails to maintain such an agent, any such process or summons may be
served by mailing a copy thereof by registered mail, or a form of mail
substantially equivalent thereto, addressed to it at its address as provided for
notices in the Indenture.

      Each of the Company and the Guarantor irrevocably waives, to the fullest
extent permitted by applicable law, all immunity (whether on the basis of
sovereignty or otherwise) from jurisdiction, attachment (both before and after
judgment) and execution to which it might

                                      A-8
<PAGE>

otherwise be entitled in any action or proceeding relating in any way to this
Note in the courts of Mexico or the United States, of the State of New York or
of any other country or jurisdiction, and the Company and the Guarantor shall
not raise a claim or cause to be pleaded any such immunity at or in respect of
any such action or proceeding.

      Each of the parties irrevocable waives, to the fullest extent permitted by
applicable law, any objection that it may now or hereafter have to the laying of
venue of any such action or proceeding in the United States District Court for
the Southern District of New York, or the Supreme Court of the State of New
York, County of New York and any claim that any such action or proceeding
brought in any such court has been brought in an inconvenient forum.

      Each of the parties hereto irrevocably waives any right it may now or
hereafter have to a trial by jury in respect of this Note.

      The Company will furnish to any Holder upon written request and without
charge a copy of the Indenture. Requests may be made to:

                    Maxcom Telecomunicaciones, S.A. de C.V.
                       Guillermo Gonzalez Camarena #2000
                         Col. Centro De Ciudad Santa Fe
                               01210 Mexico D.F.
                          Attention: Legal Department

                                       A-9
<PAGE>

                                ASSIGNMENT FORM

      To assign this Note, fill in the form below:

(I) or (we) assign and transfer this Note to: __________________________________
                                                (Insert assignee's legal name)

________________________________________________________________________________
                  (Insert assignee's soc. sec. or tax I.D. no.)

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________
              (Print or type assignee's name, address and ZIP code)

and irrevocably appoint ________________________________________________________
to transfer this Note on the books of the Company. The agent may substitute
another to act for him.

Date:  _______________

                                     Your Signature: ___________________________
                                              (Sign exactly as your name appears
                                               on the face of this Note)

Signature Guarantee*: ___________________

* Participant in a recognized Signature Guarantee Medallion Program (or other
signature guarantor acceptable to the Trustee).

                                      A-10
<PAGE>

                       OPTION OF HOLDER TO ELECT PURCHASE

      If you want to elect to have this Note purchased by the Company pursuant
to Section 3.09 of the Indenture, check the appropriate box below:

      Section 3.09 (Asset Sale Offer)     Section 4.15 (Put Offer)

      If you want to elect to have only part of the Note purchased by the
Company pursuant to Section 3.09 or Section 4.15, state the amount you elect to
have purchased:

                                            U.S.$_______________

Date:  _______________

                                          Your Signature: ______________________
                                             (Sign exactly as your name appears
                                              on the face of this Note)

                                          Tax Identification No.:_______________

Signature Guarantee*:  _________________________

* Participant in a recognized Signature Guarantee Medallion Program (or other
signature guarantor acceptable to the Trustee).

                                      A-11
<PAGE>

             SCHEDULE OF EXCHANGES OF INTERESTS IN THE GLOBAL NOTE*

      The following changes in the principal amount of this Global Note have
been made:

<TABLE>
<CAPTION>
                                                                 Principal Amount of
                                                                  this Global Note        Signature of
                      Amount of decrease   Amount of increase      following such      authorized officer
                     in Principal Amount   in Principal Amount      decrease (or       of Trustee or Note
Date of Transaction  of this Global Note   of this Global Note        increase)             Custodian
-------------------  -------------------   -------------------   -------------------   ------------------
<S>                  <C>                   <C>                   <C>                   <C>
</TABLE>

* This schedule should be included only if the Note is issued in global form.

                                      A-12
<PAGE>

                                                                       EXHIBIT B

                         [FORM OF NOTATION OF GUARANTEE]

      For value received, each Guarantor (which term includes any successor
Person under the Indenture) has, jointly and severally, unconditionally
guaranteed, to the extent set forth in the Indenture and subject to the
provisions in the Indenture originally, dated as of October 8, 2004 (the
"Indenture"), among Maxcom Telecomunicaciones, S.A. de C.V., the Guarantors
listed on Schedule I thereto and The Bank of New York, as trustee (the
"Trustee"), (a) the due and punctual payment in full of the principal of,
premium, if any, any interest, and Additional Amounts, if any, on the Notes
(including, without limitation, any interest that accrues after, or would accrue
but for, the commencement of a proceeding of the type described in Sections
6.01(i) and (j) of the Indenture) and any fees, expenses and other amounts owing
under the Indenture, whether at Stated Maturity, by acceleration, mandatory
redemption, call for redemption, upon an Asset Sale Offer, Put Offer, purchase
or otherwise, and interest on the overdue principal and (to the extent permitted
by law) interest, if any, on the Notes and any other amounts due in respect of
the Notes, and all other Obligations of the Company and the Guarantors,
including the Company's Obligations to the Holders of the Notes under the
Indenture and the Notes, and the other Guarantors' Obligations under their
Subsidiary Guarantees, whether now or hereafter existing, will be promptly paid
in full or performed, all strictly in accordance with the terms of the Indenture
and of the Notes and (b) in case of any extension of time of payment or renewal
of any Notes or any of such other obligations, the same will be promptly paid in
full when due or performed in accordance with the terms of the extension or
renewal, whether at Stated Maturity, by acceleration, mandatory redemption, call
for redemption, upon Put Offer, Asset Sale Offer, purchase or otherwise. The
obligations of the Guarantors to the Holders of Notes and to the Trustee
pursuant to the Subsidiary Guarantee and the Indenture are expressly set forth
in Article 10 of the Indenture and reference is hereby made to the Indenture for
the precise terms of the Subsidiary Guarantee. Each Holder of a Note, by
accepting the same, (a) agrees to and shall be bound by such provisions, (b)
authorizes and directs the Trustee, on behalf of such Holder, to take such
action as may be necessary or appropriate to effectuate the subordination as
provided in the Indenture and (c) appoints the Trustee attorney-in-fact of such
Holder for such purpose; provided, however, that the Indebtedness evidenced by
this Subsidiary Guarantee shall cease to be so subordinated and subject in right
of payment upon any defeasance of this Note in accordance with the provisions of
the Indenture. Capitalized terms not otherwise defined herein shall have the
meanings ascribed to such terms in the Indenture.

                                CORPORATIVO EN TELECOMUNICACIONES,
                                S.A. DE C.V.

                                By:______________________________________
                                   Name:
                                   Title:

                                       B-1
<PAGE>

                                MAXCOM SERVICIOS ADMINISTRATIVOS, S.A. DE C.V.

                                By:______________________________________
                                   Name:
                                   Title:

                                MAXCOM USA, INC.

                                By:______________________________________
                                   Name:
                                   Title:

                                       B-2
<PAGE>

                                   SCHEDULE I

                             SCHEDULE OF GUARANTORS

The following schedule lists each Guarantor under the Indenture as of the Issue
Date:

                 Corporativo en Telecomunicaciones, S.A. de C.V.

                 Maxcom Servicios Administrativos, S.A. de C.V.

                                Maxcom USA, Inc.

                                       B-3
<PAGE>

                                                                       EXHIBIT C

                         [FORM OF SUPPLEMENTAL INDENTURE
                    TO BE DELIVERED BY SUBSEQUENT GUARANTORS]

      SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"), dated as of
________________, among __________________ (the "Guaranteeing Subsidiary"), a
subsidiary of Maxcom Telecomunicaciones S.A. de C.V. (or its permitted
successor), a sociedad anonima de capital variable organized under the laws of
Mexico (the "Company"), the Company, the other Guarantors (as defined in the
Indenture referred to herein) and The Bank of New York, as trustee under the
indenture referred to below (the "Trustee").

                               W I T N E S S E T H

      WHEREAS, the Company has heretofore executed and delivered to the Trustee
an indenture (the "Indenture"), dated as of October 8, 2004, providing for the
issuance of an aggregate principal amount of up to U.S. $167,623,590 of Senior
Step-Up Notes due 2009 (the "Notes");

      WHEREAS, the Indenture provides that under certain circumstances the
Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental
indenture pursuant to which the Guaranteeing Subsidiary shall unconditionally
guarantee all of the Company's Obligations under the Notes and the Indenture on
the terms and conditions set forth herein (the "Subsidiary Guarantee"); and

      WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

      NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the
Guaranteeing Subsidiary and the Trustee mutually covenant and agree for the
equal and ratable benefit of the Holders of the Notes as follows:

      1. CAPITALIZED TERMS. Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

      2. AGREEMENT TO GUARANTEE. The Guaranteeing Subsidiary hereby agrees as
follows:

            (a) Along with all Guarantors named in the Indenture, and together
with any future Restricted Subsidiary which in accordance with Section 4.18 of
the Indenture is required in the future to guarantee the Obligations of the
Company and the Guarantors under the Subsidiary Guarantees and the Indenture,
upon execution of a supplemental indenture, to jointly and severally Guarantee
to each Holder of a Note authenticated and delivered by the Trustee and to the
Trustee and its successors and assigns, the Notes or the obligations of the
Company hereunder or thereunder, that:

                                      C-1
<PAGE>

                  (i) the principal of, premium, if any, any interest, and
            Additional Amounts, if any, on the Notes (including, without
            limitation, any interest that accrues after, or would accrue but
            for, the commencement of a proceeding of the type described in
            Sections 6.01(i) and (j) of the Indenture) and any fees, expenses
            and other amounts owing under the Indenture will be duly and
            punctually paid in full when due, whether at Stated Maturity, by
            acceleration, mandatory redemption, call for redemption, upon an
            Asset Sale Offer, Put Offer, purchase or otherwise, and interest on
            the overdue principal and (to the extent permitted by law) interest,
            if any, on the Notes and any other amounts due in respect of the
            Notes, and all other Obligations of the Company and the Guarantors,
            including the Company's Obligations to the Holders of the Notes
            under the Indenture and the Notes, and the other Guarantor's
            Obligations under their Subsidiary Guarantees, whether now or
            hereafter existing, will be promptly paid in full or performed, all
            strictly in accordance with the terms of the Indenture and of the
            Notes; and

                  (ii) in case of any extension of time of payment or renewal of
            any Notes or any of such other obligations, the same will be
            promptly paid in full when due or performed in accordance with the
            terms of the extension or renewal, whether at Stated Maturity, by
            acceleration, mandatory redemption, call for redemption, upon Put
            Offer, Asset Sale Offer, purchase or otherwise. If payment is not
            made when due of any amount so guaranteed for whatever reason,
            Guaranteeing Subsidiary shall be jointly and severally obligated to
            pay the same individually whether or not such failure to pay has
            become an Event of Default which could cause acceleration pursuant
            to Section 6.02 of the Indenture.

            (b) To waive presentation to, demand of, payment from and protest to
the Company of any of the obligations under the Indenture or the Notes and also
waive notice of protest for nonpayment. The Guaranteeing Subsidiary hereby
waives notice of any default under the Notes or under the Indenture. The
obligations of the Guaranteeing Subsidiary hereunder shall not be affected by
(i) the failure of any Holder or the Trustee to assert any claim or demand or to
enforce any right or remedy against the Company or any other Person under the
Indenture, the Notes or any other agreement or otherwise; (ii) any extension or
renewal of any thereof; (iii) any rescission, waiver, amendment or modification
of any of the terms or provisions of the Indenture, the Notes or any other
agreement; (iv) the release of any security held by any Holder, or the Trustee
or the Collateral Agent for the obligations or any of them; (v) the failure of
any Holder, or the Trustee, to exercise any right or remedy against any other
guarantor of the obligations of the Company hereunder and under the Notes; or
(vi) any change in the ownership of any such Guarantor.

            (c) The obligations set forth herein shall not be subject to any
reduction, limitation, impairment or termination for any reason, including any
claim of waiver, release, surrender, alteration or compromise, and shall not be
subject to any defense of setoff, counterclaim, recoupment or termination
whatsoever or by reason of the invalidity, illegality or unenforceability of the
obligations of the Company under the Indenture or under the Notes or otherwise.
Without limiting the generality of the foregoing, the obligations herein shall
not be discharged or impaired or otherwise affected by the failure of any Holder
or the Trustee to assert

                                      C-2
<PAGE>

any claim or demand or to enforce any remedy under the Indenture, the Notes or
any other agreement, by any waiver or modification of any thereof, by any
default, failure or delay, willful or otherwise, in the performance of the
obligations of the Company under the Indenture or under the Notes, or by any
other act or thing or omission or delay to do any other act or thing which may
or might in any manner or to any extent vary the risk of such Guarantor or would
otherwise operate as a discharge of such Guarantor as a matter of law or equity.

            (d) That the Subsidiary Guarantee to which it is an obligor shall
continue to be effective or be reinstated, as the case may be, if at any time
payment, or any part thereof, of principal of, premium, if any, on or interest
(or Additional Amounts, if any) on any obligation of the Company is rescinded or
must otherwise be restored by any Holder or the Trustee upon the bankruptcy or
reorganization of the Company or otherwise.

            (e) Upon the failure of the Company to pay the principal of,
premium, if any, on or interest (or Additional Amounts, if any) on any of its
obligations under the Indenture or under the Notes when and as the same shall
become due, whether at maturity, by acceleration, by redemption or otherwise, or
to perform or comply with any other obligation, upon receipt of written demand
by the Trustee, the Guaranteeing Subsidiary hereby agrees to pay, or cause to be
paid, in cash, to the Holders or the Trustee an amount equal to the sum of (i)
the unpaid amount of such obligations under the Indenture or under the Notes,
(ii) accrued and unpaid interest on such obligations (but only to the extent not
prohibited by law) and (iii) all other monetary obligations of the Company to
the Holders and the Trustee.

            (f) Until such time as the Notes and the other obligations of the
Company guaranteed hereby have been satisfied in full, the Guaranteeing
Subsidiary irrevocably waives any claim or other rights that it may now or
hereafter acquire against the Company or any other Guarantor that arise from the
existence, payment, performance or enforcement of its obligations hereunder, as
applicable, including, without limitation, any right of subrogation,
reimbursement, exoneration, contribution or indemnification and any right to
participate in any claim or remedy of the Holders or the Trustee against the
Company or any other Guarantor or any security, whether or not such claim,
remedy or right arises in equity or under contract, statute or common law,
including, without limitation, the right to take or receive from the Company or
any other Guarantor, directly or indirectly, in cash or other property or by
set-off or in any other manner, payment or security on account of such claim,
remedy or right.

            (g) This Subsidiary Guarantee shall not be discharged except by
complete performance of the obligations contained in the Notes and the
Indenture, and the Guaranteeing Subsidiary accepts all obligations of a
Guarantor under the Indenture.

            (h) As between the Guarantors, on the one hand, and the Holders and
the Trustee, on the other hand, (x) subject to Article 10 of the Indenture, the
maturity of the obligations of the Company guaranteed hereby may be accelerated
as provided in Article 6 of the Indenture for the purposes of its Subsidiary
Guarantee, notwithstanding any stay, injunction or other prohibition preventing
such acceleration in respect of the obligations guaranteed hereby, and (y) in
the event of any acceleration of such obligations of the Company as provided in
Article 6 of the Indenture, such obligations (whether or not due and payable)
shall further then become due and payable by the Guarantor for the purposes of
its Subsidiary Guarantee.

                                      C-3
<PAGE>

            (i) A Guarantor that makes a distribution or payment under a
Subsidiary Guarantee shall be entitled to contribution from each other Guarantor
in a pro rata amount based on the Adjusted Net Assets of each such other
Guarantor for all payments, damages and expenses incurred by that Guarantor in
discharging the Company's obligations with respect to the Notes and the
Indenture or any other Guarantor with respect to its Subsidiary Guarantee, so
long as the exercise of such right does not impair the rights of the Holders of
the Notes under the Subsidiary Guarantees.

            (j) The obligations of each Guarantor will be limited to the maximum
amount as will, after giving effect to all other contingent and fixed
liabilities of such Guarantor and after giving effect to any collections from or
payments made by or on behalf of any other Guarantor in respect of the
obligations of such other Guarantor under its Subsidiary Guarantee, or pursuant
to its contribution obligations under the Indenture, result in the obligations
of such Guarantor under its Subsidiary Guarantee, not constituting a fraudulent
conveyance or fraudulent transfer under Federal or State law or otherwise not
being void, voidable or unenforceable under any bankruptcy, reorganization,
receivership, insolvency, liquidation or other similar legislation or legal
principles under any applicable foreign law. Each Guarantor that makes a payment
or distribution under its Guarantee shall be entitled to a contribution from
each other Guarantor in a pro rata amount based on the Adjusted Net Assets of
each Guarantor.

            (k) Pursuant to Section 10.03 of the Indenture, after giving effect
to any maximum amount and any other contingent and fixed liabilities that are
relevant under any applicable bankruptcy or fraudulent conveyance laws, and
after giving effect to any collections from, rights to receive contribution from
or payments made by or on behalf of any other Guarantor in respect of the
obligations of such other Guarantor under Article 10 of the Indenture, this new
Subsidiary Guarantee shall be limited to the maximum amount permissible such
that the obligations of such Guarantor under this Subsidiary Guarantee will not
constitute a fraudulent transfer or conveyance.

            3. EXECUTION AND DELIVERY. Each Guaranteeing Subsidiary agrees that
the Subsidiary Guarantees shall remain in full force and effect notwithstanding
any failure to endorse on each Note a notation of such Subsidiary Guarantee.

            4. GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN TERMS.

            (a) The Guaranteeing Subsidiary may not consolidate with or merge
with or into (whether or not such Guarantor is the surviving Person) another
corporation, Person or entity whether or not affiliated with such Guarantor
unless:

            (i) subject to Section 10.08 of the Indenture, the Person formed by
      or surviving any such consolidation or merger (if other than a Guarantor
      or the Company) unconditionally assumes all the obligations of such
      Guarantor, pursuant to a supplemental indenture in form and substance
      reasonably satisfactory to the Trustee, under the Notes, the Indenture and
      the Subsidiary Guarantee on the terms set forth herein or therein; and

            (ii) immediately after giving effect to such transaction, no Default
      or Event of Default exists.

                                      C-4
<PAGE>

            (b) In case of any such consolidation, merger, sale or conveyance
and upon the assumption by the successor company, by supplemental indenture,
executed and delivered to the Trustee and satisfactory in form to the Trustee,
of the Subsidiary Guarantee endorsed upon the Notes and the due and punctual
performance of all of the covenants and conditions of the Indenture to be
performed by the Guarantor, such successor Person shall succeed to and be
substituted for the Guarantor with the same effect as if it had been named
herein as a Guarantor. Such successor Person thereupon may cause to be signed
any or all of the Subsidiary Guarantees to be endorsed upon all of the Notes
issuable under the Indenture which theretofore shall not have been signed by the
Company and delivered to the Trustee. All the Subsidiary Guarantees so issued
shall in all respects have the same legal rank and benefit under the Indenture
as the Subsidiary Guarantees theretofore and thereafter issued in accordance
with the terms of the Indenture as though all of such Subsidiary Guarantees had
been issued at the date of the execution of the Indenture.

            (c) Except as set forth in Articles 4 and 5 of the Indenture, and
notwithstanding clauses (a) and (b) above, nothing contained in the Indenture or
in any of the Notes shall prevent any consolidation or merger of a Guarantor
with or into the Company or another Guarantor, or shall prevent any sale or
conveyance of the property of a Guarantor as an entirety or substantially as an
entirety to the Company or another Guarantor.

      5.    RELEASES.

      (a) In the event of a sale or other disposition of all of the assets of
any Guarantor, by way of merger, consolidation or otherwise, or a sale or other
disposition of all to the capital stock of any Guarantor, in each case to a
Person that is not (either before or after giving effect to such transaction) a
Restricted Subsidiary of the Company, then such Guarantor (in the event of a
sale or other disposition, by way of merger, consolidation or otherwise, of all
of the capital stock of such Guarantor) or the corporation acquiring the
property (in the event of a sale or other disposition of all or substantially
all of the assets of such Guarantor) will be released and relieved of any
obligations under its Subsidiary Guarantee; provided that the net proceeds of
such sale or other disposition are applied in accordance with the applicable
provisions of the Indenture, including without limitation Section 4.10 of the
Indenture. Upon delivery by the Company to the Trustee of an Officers'
Certificate and an Opinion of Counsel to the effect that such sale or other
disposition was made by the Company in accordance with the provisions of the
Indenture, including without limitation Section 4.10 of the Indenture, the
Trustee shall execute any documents reasonably required in order to evidence the
release of any Guarantor from its obligations under its Subsidiary Guarantee.

      (b) In the case of a conveyance, transfer or lease of all or substantially
all of the Company's assets, no Guarantor shall be released from be released or
relieved of any obligations under its Subsidiary Guarantee unless such
transaction (i) involves a Successor Company other than the Company which
expressly assumes, by an indenture supplemental hereto, executed and delivered
to the Trustee, in form reasonably satisfactory to the Trustee, all of the
obligations of the Company under the Notes and the Indenture and (ii) satisfies
the other conditions set forth in Section 5.01(a)(ii) of the Indenture, in which
case the Company and each Guarantor will be released and relieved of any and all
obligations hereunder, under the Notes, any Subsidiary Guarantee delivered in
connection with the Indenture, and any other instrument, undertaking or

                                      C-5
<PAGE>

agreement delivered by the Company or a Guarantor in connection with the
Indenture (other than any Officers' Certificate). Upon delivery by the Company
to the Trustee of an Officers' Certificate to the effect that such conveyance,
transfer, or lease was made by the Company in accordance with the provisions of
the Indenture, including without limitation Section 5.01(a)(ii), the Trustee
shall execute any documents reasonably required in order to evidence the release
the Company and each Guarantor from their respective obligations under the
Indenture, under the Notes, under any Subsidiary Guarantee, and under any other
instrument, undertaking or agreement delivered by the Company or a Guarantor in
connection with the Indenture (other than any Officers' Certificate).

            (c) Any Guarantor not released from its obligations under its
Subsidiary Guarantee shall remain liable for the full amount of principal of and
interest on the Notes and for the other obligations of any Guarantor under the
Indenture as provided in Article 11 of the Indenture.

      6. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator or stockholder of the Guaranteeing Subsidiary,
as such, shall have any liability for any obligations of the Company or any
Guarantor under the Notes, any Subsidiary Guarantees, the Indenture or this
Supplemental Indenture or for any claim based on, in respect of, or by reason
of, such obligations or their creation. Each Holder of the Notes by accepting a
Note waives and releases all such liability. The waiver and release are part of
the consideration for issuance of the Notes. Such waiver may not be effective to
waive liabilities under the federal securities laws and it is the view of the
SEC that such a waiver is against public policy..

      7. GOVERNING LAW AND SUBMISSION TO JURISDICTION. This Supplemental
Indenture and all of the rights and obligations of the parties hereto shall be
governed by and construed in accordance with the laws of the State of New York
without giving effect to the conflict of law provisions thereof, and if any
dispute or controversy related to or arising out of this Supplemental Indenture
is brought before a Mexican court, the parties hereto agree that this
Supplemental Indenture shall be governed by and construed in accordance with the
laws of the State of New York without giving effect to the conflict of law
provisions thereof.

      Any action or proceeding relating in any way to this Supplemental
Indenture may be brought and enforced in the federal courts of the United States
for the Southern District of New York, and each of the parties hereto
irrevocably submits to the nonexclusive jurisdiction of each such court in
respect of any such action or proceeding and the Company and the Guarantor
hereby expressly waive any jurisdiction rights they may be entitled to by reason
of their present or future domicile or otherwise; provided, that if for whatever
reason the federal courts of the United States for the Southern District of New
York will not or cannot hear such action or proceeding, it may be brought and
enforced in the courts of the State of New York in The City of New York, Borough
of Manhattan. Each of the Company and each of the Guarantors irrevocably
appoints CT Corporation System, with offices at 111 Eighth Avenue, 13th Floor,
New York, New York 10011, as its agent to receive service of process or other
legal summons for purposes of any such action or proceeding. So long as the
Company or the Guarantors has any obligation under this Supplemental Indenture,
it will maintain a duly appointed agent in The City of New York, Borough of
Manhattan for the service of such process or summons, and if it fails to
maintain such an agent, any such process or summons may be served by mailing a
copy

                                      C-6
<PAGE>

thereof by registered mail, or a form of mail substantially equivalent thereto,
addressed to it at its address as provided for notices hereunder.

      Each of the Company and the Guarantors irrevocably waives, to the fullest
extent permitted by applicable law, all immunity (whether on the basis of
sovereignty or otherwise) from jurisdiction, attachment (both before and after
judgment) and execution to which it might otherwise be entitled in any action or
proceeding relating in any way to this Supplemental Indenture in the courts of
Mexico or the United States, of the State of New York or of any other country or
jurisdiction, and the Company and the Guarantors shall not raise a claim or
cause to be pleaded any such immunity at or in respect of any such action or
proceeding. Each of the parties irrevocable waives, to the fullest extent
permitted by applicable law, any objection that it may now or hereafter have to
the laying of venue of any such action or proceeding in the United States
District Court for the Southern District of New York, or the Supreme Court of
the State of New York, County of New York and any claim that any such action or
proceeding brought in any such court has been brought in an inconvenient forum.

      Each of the parties hereto irrevocably waives any right it may now or
hereafter have to a trial by jury in respect of this Supplemental Indenture.

      8. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

      9. EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not affect the construction hereof.

      10. THE TRUSTEE. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture or for or in respect of the recitals contained herein, and in the
Notes, except the Trustee's certificates of authentication, all of which
recitals are made solely by the Guaranteeing Subsidiary and the Company and the
Trustee or any Authenticating Agent assumes no responsibility for their
correctness. The Trustee or any Authenticating Agent shall not be accountable
for the use or application by the Company of the Notes or the proceeds thereof.

                                      C-7
<PAGE>

      IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

Dated:  _______________, ____

                                      [GUARANTEEING SUBSIDIARY]

                                      By:  ___________________________
                                      Name:
                                      Title:

                                      MAXCOM TELECOMUNICACIONES, S.A. DE C.V.

                                      By:  _____________________________
                                      Name:
                                      Title:

                                      MAXCOM SERVICIOS ADMINISTRATIVOS,
                                      S.A. DE C.V.

                                      By:______________________________________
                                           Name:
                                           Title:

                                      MAXCOM USA, INC.

                                      By:______________________________________
                                           Name:
                                           Title:

                                      [OTHER EXISTING GUARANTORS]

                                      By:  _______________________________
                                      Name:
                                      Title:

                                       C-8
<PAGE>

                                      THE BANK OF NEW YORK
                                       as Trustee

                                      By:  _______________________________
                                      Name:
                                      Title:

                                       C-9